Bump sidekiq from 5.0.5 to 6.0.4

Bumps [sidekiq](https://github.com/mperham/sidekiq) from 5.0.5 to 6.0.4.
- [Release notes](https://github.com/mperham/sidekiq/releases)
- [Changelog](https://github.com/mperham/sidekiq/blob/master/Changes.md)
- [Commits](sidekiq/sidekiq@v5.0.5...v6.0.4)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

Gemfile.lock

@@ -53,7 +53,7 @@ GEM
       activesupport
     coderay (1.1.2)
     concurrent-ruby (1.1.5)
-    connection_pool (2.2.1)
+    connection_pool (2.2.2)
     crass (1.0.5)
     debug_inspector (0.0.3)
     devise (4.6.2)
@@ -111,12 +111,12 @@ GEM
       binding_of_caller (>= 0.7)
       pry (>= 0.9.11)
     puma (3.12.2)
-    rack (2.0.8)
+    rack (2.1.2)
     rack-attack (5.0.1)
       rack
     rack-cors (1.0.5)
       rack (>= 1.6.0)
-    rack-protection (2.0.0)
+    rack-protection (2.0.8.1)
       rack
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
@@ -147,7 +147,7 @@ GEM
     rb-fsevent (0.10.2)
     rb-inotify (0.9.10)
       ffi (>= 0.5.0, < 2)
-    redis (4.0.1)
+    redis (4.1.3)
     redis-actionpack (5.0.2)
       actionpack (>= 4.0, < 6)
       redis-rack (>= 1, < 3)
@@ -183,11 +183,11 @@ GEM
       rspec-mocks (~> 3.1.0)
       rspec-support (~> 3.1.0)
     rspec-support (3.1.2)
-    sidekiq (5.0.5)
-      concurrent-ruby (~> 1.0)
-      connection_pool (~> 2.2, >= 2.2.0)
-      rack-protection (>= 1.5.0)
-      redis (>= 3.3.4, < 5)
+    sidekiq (6.0.4)
+      connection_pool (>= 2.2.2)
+      rack (>= 2.0.0)
+      rack-protection (>= 2.0.0)
+      redis (>= 4.1.0)
     spring (2.0.2)
       activesupport (>= 4.2)
     spring-watcher-listen (2.0.1)