Drop 2.7 from rubocop

Author: sjha4

.github/workflows/test.yml

@@ -15,6 +15,7 @@ jobs:
     name: Rubocop
     uses: theforeman/actions/.github/workflows/rubocop.yml@v0
     with:
+      ruby: "3.0"
       command: bundle exec rubocop --parallel --format github
 
   test:

.rubocop.yml

@@ -1,7 +1,7 @@
 inherit_from: .rubocop_todo.yml
 
 AllCops:
-  TargetRubyVersion: 2.7
+  TargetRubyVersion: 3.0
 
 # Don't prefer is_a? over kind_of?
 Style/ClassCheck: