Bump Sidekiq to 5.2.7

Fixes minor bugs
(https://github.com/mperham/sidekiq/blob/master/Changes.md#526) and
keeps version used with gitlab-monitor consistent.

Gemfile

@@ -158,7 +158,7 @@ gem 'state_machines-activerecord', '~> 0.5.1'
 gem 'acts-as-taggable-on', '~> 6.0'
 
 # Background jobs
-gem 'sidekiq', '~> 5.2.1'
+gem 'sidekiq', '~> 5.2.7'
 gem 'sidekiq-cron', '~> 1.0'
 gem 'redis-namespace', '~> 1.6.0'
 gem 'gitlab-sidekiq-fetcher', '~> 0.4.0', require: 'sidekiq-reliable-fetch'

Gemfile.lock

@@ -846,7 +846,7 @@ GEM
       rack
     shoulda-matchers (3.1.2)
       activesupport (>= 4.0.0)
-    sidekiq (5.2.5)
+    sidekiq (5.2.7)
       connection_pool (~> 2.2, >= 2.2.2)
       rack (>= 1.5.0)
       rack-protection (>= 1.5.0)
@@ -1183,7 +1183,7 @@ DEPENDENCIES
   settingslogic (~> 2.0.9)
   sham_rack (~> 1.3.6)
   shoulda-matchers (~> 3.1.2)
-  sidekiq (~> 5.2.1)
+  sidekiq (~> 5.2.7)
   sidekiq-cron (~> 1.0)
   simple_po_parser (~> 1.1.2)
   simplecov (~> 0.14.0)