Merge branch 'frozen-string-enable-lib-gitlab-hook-data' into 'master'

Enable frozen string for hook data specs

See merge request gitlab-org/gitlab!20602

spec/lib/gitlab/hook_data/base_builder_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::HookData::BaseBuilder do

spec/lib/gitlab/hook_data/issuable_builder_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::HookData::IssuableBuilder do

spec/lib/gitlab/hook_data/issue_builder_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::HookData::IssueBuilder do

spec/lib/gitlab/hook_data/merge_request_builder_spec.rb

+# frozen_string_literal: true
+
 require 'spec_helper'
 
 describe Gitlab::HookData::MergeRequestBuilder do