Improve rubocop related CI workflows

Author: st0012

.github/workflows/test.yml

@@ -45,5 +45,18 @@ jobs:
         RUBYOPT: --enable-frozen_string_literal
     - if: ${{ matrix.ruby == 'head' && startsWith(matrix.os, 'ubuntu') }}
       run: bundle exec rake rdoc
-    - if: ${{ matrix.ruby == 'head' && startsWith(matrix.os, 'ubuntu') }}
-      run: bundle exec rake rubocop
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.3"
+          bundler-cache: true
+      - name: Run rubocop
+        run: bundle exec rubocop
+        # Just to make sure the format_generated_files task is working
+      - name: Sanity check for the format_generated_files task
+        run: |
+          bundle exec rake generate format_generated_files