Bump sidekiq from 5.0.3 to 5.2.8

Bumps [sidekiq](https://github.com/mperham/sidekiq) from 5.0.3 to 5.2.8.
- [Release notes](https://github.com/mperham/sidekiq/releases)
- [Changelog](https://github.com/mperham/sidekiq/blob/main/Changes.md)
- [Commits](https://github.com/mperham/sidekiq/compare/v5.0.3...v5.2.8)

---
updated-dependencies:
- dependency-name: sidekiq
  dependency-type: direct:production
...

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

Gemfile.lock

@@ -128,8 +128,8 @@ GEM
       compass (~> 1.0.0)
       sass-rails (< 5.1)
       sprockets (< 4.0)
-    concurrent-ruby (1.1.7)
-    connection_pool (2.2.1)
+    concurrent-ruby (1.1.9)
+    connection_pool (2.2.5)
     crack (0.4.3)
       safe_yaml (~> 1.0.0)
     crass (1.0.6)
@@ -247,7 +247,9 @@ GEM
     mime-types (3.2.2)
       mime-types-data (~> 3.2015)
     mime-types-data (3.2018.0812)
-    mimemagic (0.3.3)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.1)
     mini_portile2 (2.4.0)
     minitest (5.14.2)
@@ -505,11 +507,11 @@ GEM
     shoulda-context (1.2.2)
     shoulda-matchers (2.8.0)
       activesupport (>= 3.0.0)
-    sidekiq (5.0.3)
-      concurrent-ruby (~> 1.0)
-      connection_pool (~> 2.2, >= 2.2.0)
+    sidekiq (5.2.8)
+      connection_pool (~> 2.2, >= 2.2.2)
+      rack (< 2.1.0)
       rack-protection (>= 1.5.0)
-      redis (~> 3.3, >= 3.3.3)
+      redis (>= 3.3.5, < 5)
     sidekiq-failures (1.0.0)
       sidekiq (>= 4.0.0)
     sidekiq-scheduler (2.1.6)