Revert Sidekiq queue lib to working version

Newer Sidekiq versions require new Rails versions.

Gemfile

@@ -73,7 +73,7 @@ gem 'sass-rails'
 gem 'coffee-rails', '~> 4.2.0'
 gem 'sentry-ruby'
 gem 'sentry-rails'
-gem 'sidekiq'
+gem 'sidekiq', '< 7'
 gem 'simplecov', :require => false, :group => :test
 gem 'simple_form'
 gem 'sitemap_generator'

Gemfile.lock

@@ -91,7 +91,7 @@ GEM
       debug_inspector (>= 0.0.1)
     bitmask_attributes (1.0.0)
       activerecord (>= 3.1)
-    bootsnap (1.16.0)
+    bootsnap (1.17.0)
       msgpack (~> 1.2)
     bootstrap4-kaminari-views (1.0.1)
       kaminari (>= 0.13)
@@ -341,7 +341,7 @@ GEM
     nenv (0.3.0)
     nest (3.2.0)
       redic
-    net-imap (0.4.1)
+    net-imap (0.4.3)
       date
       net-protocol
     net-pop (0.1.2)
@@ -397,7 +397,7 @@ GEM
     public_suffix (5.0.3)
     puma (6.4.0)
       nio4r (~> 2.0)
-    racc (1.7.1)
+    racc (1.7.2)
     rack (2.2.8)
     rack-attack (6.7.0)
       rack (>= 1.0, < 4)
@@ -443,7 +443,7 @@ GEM
       rake (>= 0.8.7)
       thor (>= 0.19.0, < 2.0)
     rainbow (3.1.1)
-    rake (13.0.6)
+    rake (13.1.0)
     ransack (2.5.0)
       activerecord (>= 5.2.4)
       activesupport (>= 5.2.4)
@@ -452,15 +452,15 @@ GEM
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rdoc (6.3.3)
-    recaptcha (5.15.0)
+    recaptcha (5.16.0)
     record_tag_helper (1.0.1)
       actionview (>= 5)
     redcarpet (3.6.0)
     redic (1.5.3)
       hiredis
-    redis (5.0.7)
-      redis-client (>= 0.9.0)
-    redis-client (0.17.0)
+    redis (5.0.8)
+      redis-client (>= 0.17.0)
+    redis-client (0.18.0)
       connection_pool
     regexp_parser (2.8.2)
     request_store (1.5.1)
@@ -521,11 +521,10 @@ GEM
     shellany (0.0.1)
     shoulda-matchers (5.3.0)
       activesupport (>= 5.2.0)
-    sidekiq (7.1.6)
-      concurrent-ruby (< 2)
-      connection_pool (>= 2.3.0)
-      rack (>= 2.2.4)
-      redis-client (>= 0.14.0)
+    sidekiq (6.5.5)
+      connection_pool (>= 2.2.2)
+      rack (~> 2.0)
+      redis (>= 4.5.0)
     simple_form (5.3.0)
       actionpack (>= 5.2)
       activemodel (>= 5.2)
@@ -556,7 +555,7 @@ GEM
       unicode-display_width (>= 1.1.1, < 3)
     test-unit (3.6.1)
       power_assert
-    thor (1.2.2)
+    thor (1.3.0)
     thread_safe (0.3.6)
     tilt (2.3.0)
     timeout (0.4.0)
@@ -695,7 +694,7 @@ DEPENDENCIES
   sentry-rails
   sentry-ruby
   shoulda-matchers
-  sidekiq
+  sidekiq (< 7)
   simple_form
   simplecov
   sitemap_generator