Bump sidekiq from 6.4.0 to 7.1.4 in /backend

Bumps [sidekiq](https://github.com/sidekiq/sidekiq) from 6.4.0 to 7.1.4.
- [Changelog](https://github.com/sidekiq/sidekiq/blob/main/Changes.md)
- [Commits](sidekiq/sidekiq@v6.4.0...v7.1.4)

---
updated-dependencies:
- dependency-name: sidekiq
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

backend/Gemfile

@@ -31,7 +31,7 @@ gem "omniauth-facebook", "3.0.0"
 gem "colored", "~> 1.2"
 
 # Background jobs
-gem "sidekiq", "~> 6.4"
+gem "sidekiq", "~> 7.1"
 
 # Structured seed data
 gem "seedbank"

backend/Gemfile.lock

@@ -101,7 +101,7 @@ GEM
       descendants_tracker (~> 0.0.1)
     colored (1.2)
     concurrent-ruby (1.2.2)
-    connection_pool (2.2.5)
+    connection_pool (2.4.1)
     countries (4.0.1)
       i18n_data (~> 0.13.0)
       sixarm_ruby_unaccent (~> 1.1)
@@ -310,7 +310,7 @@ GEM
     pusher-signature (0.1.8)
     racc (1.7.1)
     racc (1.7.1-java)
-    rack (2.2.7)
+    rack (2.2.8)
     rack-cors (1.1.1)
       rack (>= 2.0.0)
     rack-test (2.1.0)
@@ -351,7 +351,8 @@ GEM
       thor (~> 1.0)
     rainbow (3.1.1)
     rake (13.0.6)
-    redis (4.5.1)
+    redis-client (0.17.0)
+      connection_pool
     regexp_parser (2.8.1)
     request_store (1.5.0)
       rack (>= 1.4)
@@ -399,10 +400,11 @@ GEM
       rake (>= 10.0)
     shoulda-matchers (5.3.0)
       activesupport (>= 5.2.0)
-    sidekiq (6.4.0)
-      connection_pool (>= 2.2.2)
-      rack (~> 2.0)
-      redis (>= 4.2.0)
+    sidekiq (7.1.4)
+      concurrent-ruby (< 2)
+      connection_pool (>= 2.3.0)
+      rack (>= 2.2.4)
+      redis-client (>= 0.14.0)
     simplecov (0.22.0)
       docile (~> 1.1)
       simplecov-html (~> 0.11)
@@ -515,7 +517,7 @@ DEPENDENCIES
   ruby-progressbar
   seedbank
   shoulda-matchers
-  sidekiq (~> 6.4)
+  sidekiq (~> 7.1)
   simplecov
   standardrb
   symmetric-encryption