Bump sidekiq from 5.2.9 to 6.2.1 (#9514)

Bumps [sidekiq](https://github.com/mperham/sidekiq) from 5.2.9 to 6.2.1.
- [Release notes](https://github.com/mperham/sidekiq/releases)
- [Changelog](https://github.com/mperham/sidekiq/blob/master/Changes.md)
- [Commits](sidekiq/sidekiq@v5.2.9...v6.2.1)

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

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

Gemfile.lock

@@ -99,7 +99,7 @@ GEM
     composite_primary_keys (11.2.0)
       activerecord (~> 5.2.1)
     concurrent-ruby (1.1.8)
-    connection_pool (2.2.3)
+    connection_pool (2.2.5)
     crack (0.4.5)
       rexml
     crass (1.0.6)
@@ -375,8 +375,6 @@ GEM
     rack-openid (1.4.2)
       rack (>= 1.1.0)
       ruby-openid (>= 2.1.8)
-    rack-protection (2.0.8.1)
-      rack
     rack-proxy (0.6.5)
       rack
     rack-test (1.1.0)
@@ -430,7 +428,7 @@ GEM
       tilt
     recaptcha (4.14.0)
       json
-    redis (4.1.4)
+    redis (4.2.5)
     regexp_parser (2.1.1)
     representable (3.0.4)
       declarative (< 0.1.0)
@@ -498,11 +496,10 @@ GEM
     semantic_range (2.3.1)
     sentry-raven (3.1.2)
       faraday (>= 1.0)
-    sidekiq (5.2.9)
-      connection_pool (~> 2.2, >= 2.2.2)
+    sidekiq (6.2.1)
+      connection_pool (>= 2.2.2)
       rack (~> 2.0)
-      rack-protection (>= 1.5.0)
-      redis (>= 3.3.5, < 4.2)
+      redis (>= 4.2.0)
     signet (0.15.0)
       addressable (~> 2.3)
       faraday (>= 0.17.3, < 2.0)