Bump sidekiq from 5.2.2 to 6.0.0

Bumps [sidekiq](https://github.com/mperham/sidekiq) from 5.2.2 to 6.0.0.
- [Release notes](https://github.com/mperham/sidekiq/releases)
- [Changelog](https://github.com/mperham/sidekiq/blob/master/Changes.md)
- [Commits](sidekiq/sidekiq@v5.2.2...v6.0.0)

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

Gemfile

@@ -22,7 +22,7 @@ gem 'puma', '~> 3.12'
 gem 'rack-cors'
 gem 'sass-rails', '~> 5.0'
 gem 'sentry-raven'
-gem 'sidekiq', '< 6'
+gem 'sidekiq', '< 7'
 gem 'skylight'
 gem 'turbolinks', '~> 5'
 gem 'tzinfo-data'

Gemfile.lock

@@ -333,11 +333,11 @@ GEM
       faraday (>= 0.7.6, < 1.0)
     sexp_processor (4.13.0)
     shellany (0.0.1)
-    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)
+    sidekiq (6.0.0)
+      connection_pool (>= 2.2.2)
+      rack (>= 2.0.0)
+      rack-protection (>= 2.0.0)
+      redis (>= 4.1.0)
     simplecov (0.16.1)
       docile (~> 1.1)
       json (>= 1.8, < 3)
@@ -447,7 +447,7 @@ DEPENDENCIES
   rspec-sidekiq
   sass-rails (~> 5.0)
   sentry-raven
-  sidekiq (< 6)
+  sidekiq (< 7)
   skylight
   spring
   spring-watcher-listen (~> 2.0.0)