Add `null: true` to timestamps in migrations that does not define it

This is to ensure that migrations will still be consitent when we will
upgrade to Rails 5 which default to `null: false` for timestamps
columns.

Fixes #23666.
Signed-off-by: Rémy Coutable <remy@rymai.me>

db/migrate/20130319214458_create_forked_project_links.rb

@@ -5,7 +5,7 @@ class CreateForkedProjectLinks < ActiveRecord::Migration
       t.integer :forked_to_project_id, null: false
       t.integer :forked_from_project_id, null: false
 
-      t.timestamps
+      t.timestamps null: true
     end
     add_index :forked_project_links, :forked_to_project_id, unique: true
   end

db/migrate/20130506090604_create_deploy_keys_projects.rb

@@ -5,7 +5,7 @@ class CreateDeployKeysProjects < ActiveRecord::Migration
       t.integer :deploy_key_id, null: false
       t.integer :project_id, null: false
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20130617095603_create_users_groups.rb

@@ -6,7 +6,7 @@ class CreateUsersGroups < ActiveRecord::Migration
       t.integer :group_id, null: false
       t.integer :user_id, null: false
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20130711063759_create_project_group_links.rb

@@ -5,7 +5,7 @@ class CreateProjectGroupLinks < ActiveRecord::Migration
       t.integer :project_id, null: false
       t.integer :group_id, null: false
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20131112114325_create_broadcast_messages.rb

@@ -7,7 +7,7 @@ class CreateBroadcastMessages < ActiveRecord::Migration
       t.datetime :ends_at
       t.integer :alert_type
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20140122112253_create_merge_request_diffs.rb

@@ -7,7 +7,7 @@ class CreateMergeRequestDiffs < ActiveRecord::Migration
       t.text :st_diffs, null: true
       t.integer :merge_request_id, null: false
 
-      t.timestamps
+      t.timestamps null: true
     end
 
     if ActiveRecord::Base.configurations[Rails.env]['adapter'] =~ /^mysql/

db/migrate/20140209025651_create_emails.rb

@@ -5,7 +5,7 @@ class CreateEmails < ActiveRecord::Migration
       t.integer  :user_id, null: false
       t.string   :email, null: false
       
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :emails, :user_id

db/migrate/20140625115202_create_users_star_projects.rb

@@ -4,7 +4,7 @@ class CreateUsersStarProjects < ActiveRecord::Migration
     create_table :users_star_projects do |t|
       t.integer :project_id, null: false
       t.integer :user_id, null: false
-      t.timestamps
+      t.timestamps null: true
     end
     add_index :users_star_projects, :user_id
     add_index :users_star_projects, :project_id

db/migrate/20140729134820_create_labels.rb

@@ -6,7 +6,7 @@ class CreateLabels < ActiveRecord::Migration
       t.string :color
       t.integer :project_id
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20140729140420_create_label_links.rb

@@ -6,7 +6,7 @@ class CreateLabelLinks < ActiveRecord::Migration
       t.integer :target_id
       t.string :target_type
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20140914113604_add_members_table.rb

@@ -9,7 +9,7 @@ class AddMembersTable < ActiveRecord::Migration
       t.integer :notification_level, null: false
       t.string  :type
 
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :members, :type

db/migrate/20140914173417_remove_old_member_tables.rb

@@ -12,7 +12,7 @@ class RemoveOldMemberTables < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.integer :notification_level, null: false, default: 3
 
-      t.timestamps
+      t.timestamps null: true
     end
 
     create_table :users_projects do |t|
@@ -21,7 +21,7 @@ class RemoveOldMemberTables < ActiveRecord::Migration
       t.integer :user_id, null: false
       t.integer :notification_level, null: false, default: 3
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20141118150935_add_audit_event.rb

@@ -13,7 +13,7 @@ class AddAuditEvent < ActiveRecord::Migration
       # Details for the event
       t.text  :details
 
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :audit_events, :author_id

db/migrate/20141216155758_create_doorkeeper_tables.rb

@@ -7,7 +7,7 @@ class CreateDoorkeeperTables < ActiveRecord::Migration
       t.string  :secret,       null: false
       t.text    :redirect_uri, null: false
       t.string  :scopes,       null: false, default: ''
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :oauth_applications, :uid, unique: true

db/migrate/20150108073740_create_application_settings.rb

@@ -8,7 +8,7 @@ class CreateApplicationSettings < ActiveRecord::Migration
       t.boolean :gravatar_enabled
       t.text :sign_in_text
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20150313012111_create_subscriptions_table.rb

@@ -6,7 +6,7 @@ class CreateSubscriptionsTable < ActiveRecord::Migration
       t.references :subscribable, polymorphic: true
       t.boolean :subscribed
       
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :subscriptions, 

db/migrate/20150806104937_create_abuse_reports.rb

@@ -6,7 +6,7 @@ class CreateAbuseReports < ActiveRecord::Migration
       t.integer :user_id
       t.text :message
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20151103134857_create_lfs_objects.rb

@@ -5,7 +5,7 @@ class CreateLfsObjects < ActiveRecord::Migration
       t.string :oid, null: false, unique: true
       t.integer :size, null: false
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20151103134958_create_lfs_objects_projects.rb

@@ -5,7 +5,7 @@ class CreateLfsObjectsProjects < ActiveRecord::Migration
       t.integer :lfs_object_id, null: false
       t.integer :project_id, null: false
 
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :lfs_objects_projects, :project_id

db/migrate/20151105094515_create_releases.rb

@@ -6,7 +6,7 @@ class CreateReleases < ActiveRecord::Migration
       t.text :description
       t.integer :project_id
 
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :releases, :project_id

db/migrate/20160212123307_create_tasks.rb

@@ -9,7 +9,7 @@ class CreateTasks < ActiveRecord::Migration
       t.integer :action, null: false
       t.string :state, null: false, index: true
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end

db/migrate/20160416180807_add_award_emoji.rb

@@ -6,7 +6,7 @@ class AddAwardEmoji < ActiveRecord::Migration
       t.references :user
       t.references :awardable, polymorphic: true
 
-      t.timestamps
+      t.timestamps null: true
     end
 
     add_index :award_emoji, :user_id

db/migrate/20160831214002_create_project_features.rb

@@ -10,7 +10,7 @@ class CreateProjectFeatures < ActiveRecord::Migration
       t.integer  :snippets_access_level
       t.integer  :builds_access_level
 
-      t.timestamps
+      t.timestamps null: true
     end
   end
 end