Bump Sidekiq 5.1.3 to 5.2.1

The most significant change in this version is that the default
concurrency has been lowered from 25 to 10 (https://github.com/mperham/sidekiq/issues/3892).
This doesn't affect omnibus-gitlab because the concurrency is controlled via a
setting that defaults to 25 anyway and is passed in via the `-c` command-line
parameter.

However, source installations (including the GDK) will have to either specify
the concurrency in `sidekiq.yml` or use the `-c` option.

Full list of changes: https://github.com/mperham/sidekiq/blob/master/Changes.md

Gemfile

@@ -170,7 +170,7 @@ gem 'state_machines-activerecord', '~> 0.5.1'
 gem 'acts-as-taggable-on', '~> 5.0'
 
 # Background jobs
-gem 'sidekiq', '~> 5.1'
+gem 'sidekiq', '~> 5.2.1'
 gem 'sidekiq-cron', '~> 0.6.0'
 gem 'redis-namespace', '~> 1.6.0'
 gem 'sidekiq-limit_fetch', '~> 3.4', require: false

Gemfile.lock

@@ -133,7 +133,7 @@ GEM
     concurrent-ruby (1.0.5)
     concurrent-ruby-ext (1.0.5)
       concurrent-ruby (= 1.0.5)
-    connection_pool (2.2.1)
+    connection_pool (2.2.2)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     crass (1.0.4)
@@ -649,7 +649,7 @@ GEM
       httpclient (>= 2.4)
       multi_json (>= 1.3.6)
       rack (>= 1.1)
-    rack-protection (2.0.1)
+    rack-protection (2.0.3)
       rack
     rack-proxy (0.6.0)
       rack
@@ -843,9 +843,8 @@ GEM
       rack
     shoulda-matchers (3.1.2)
       activesupport (>= 4.0.0)
-    sidekiq (5.1.3)
-      concurrent-ruby (~> 1.0)
-      connection_pool (~> 2.2, >= 2.2.0)
+    sidekiq (5.2.1)
+      connection_pool (~> 2.2, >= 2.2.2)
       rack-protection (>= 1.5.0)
       redis (>= 3.3.5, < 5)
     sidekiq-cron (0.6.0)
@@ -1166,7 +1165,7 @@ DEPENDENCIES
   settingslogic (~> 2.0.9)
   sham_rack (~> 1.3.6)
   shoulda-matchers (~> 3.1.2)
-  sidekiq (~> 5.1)
+  sidekiq (~> 5.2.1)
   sidekiq-cron (~> 0.6.0)
   sidekiq-limit_fetch (~> 3.4)
   simple_po_parser (~> 1.1.2)

Gemfile.rails5.lock

@@ -136,7 +136,7 @@ GEM
     concurrent-ruby (1.0.5)
     concurrent-ruby-ext (1.0.5)
       concurrent-ruby (= 1.0.5)
-    connection_pool (2.2.1)
+    connection_pool (2.2.2)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     crass (1.0.4)
@@ -653,7 +653,7 @@ GEM
       httpclient (>= 2.4)
       multi_json (>= 1.3.6)
       rack (>= 1.1)
-    rack-protection (2.0.1)
+    rack-protection (2.0.3)
       rack
     rack-proxy (0.6.0)
       rack
@@ -851,9 +851,8 @@ GEM
       rack
     shoulda-matchers (3.1.2)
       activesupport (>= 4.0.0)
-    sidekiq (5.1.3)
-      concurrent-ruby (~> 1.0)
-      connection_pool (~> 2.2, >= 2.2.0)
+    sidekiq (5.2.1)
+      connection_pool (~> 2.2, >= 2.2.2)
       rack-protection (>= 1.5.0)
       redis (>= 3.3.5, < 5)
     sidekiq-cron (0.6.0)
@@ -1176,7 +1175,7 @@ DEPENDENCIES
   settingslogic (~> 2.0.9)
   sham_rack (~> 1.3.6)
   shoulda-matchers (~> 3.1.2)
-  sidekiq (~> 5.1)
+  sidekiq (~> 5.2.1)
   sidekiq-cron (~> 0.6.0)
   sidekiq-limit_fetch (~> 3.4)
   simple_po_parser (~> 1.1.2)