Pin sidekiq to version 5.x

Now that Sidekiq 6 has been released, which removes the ability to daemonize
sidekiq, we must pin sidekiq until we are daemonizing sidekiq via systemd (vs.
the sidekiq executable in the bundle). Note the tracking issue in
capistrano-sidekiq: seuros/capistrano-sidekiq#224

Gemfile

@@ -32,7 +32,8 @@ gem 'dor-services-client'
 gem 'dor-workflow-client', '~> 3.4', '>= 3.4.2'
 gem 'honeybadger'
 gem 'okcomputer'
-gem 'sidekiq'
+# TODO: Unpin from 5.x once we have switched to using systemd to manage the sidekiq daemon
+gem 'sidekiq', '~> 5.2'
 gem 'simple_form'
 gem 'whenever', '~> 1.0', require: false
 

Gemfile.lock

@@ -288,11 +288,11 @@ GEM
       unicode-display_width (>= 1.4.0, < 1.7)
     ruby-progressbar (1.10.1)
     ruby_dep (1.5.0)
-    sidekiq (6.0.0)
-      connection_pool (>= 2.2.2)
-      rack (>= 2.0.0)
-      rack-protection (>= 2.0.0)
-      redis (>= 4.1.0)
+    sidekiq (5.2.7)
+      connection_pool (~> 2.2, >= 2.2.2)
+      rack (>= 1.5.0)
+      rack-protection (>= 1.5.0)
+      redis (>= 3.3.5, < 5)
     simple_form (4.1.0)
       actionpack (>= 5.0)
       activemodel (>= 5.0)
@@ -362,7 +362,7 @@ DEPENDENCIES
   rspec-rails (~> 3.8)
   rspec_junit_formatter
   rubocop
-  sidekiq
+  sidekiq (~> 5.2)
   simple_form
   simplecov
   spring