chore(ci): run linting as separate job

.github/workflows/ruby.yml

@@ -18,9 +18,10 @@ jobs:
           - '3.2'
           - '3.3'
         rails-version:
-          - '6.1'
           - '7.0'
           - '7.1'
+          - '7.2'
+
     env:
       BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/rails_${{ matrix.rails-version }}.gemfile
 
@@ -33,4 +34,19 @@ jobs:
         bundler-cache: true # runs 'bundle install' and caches installed gems automatically
 
     - name: Run tests
-      run: bundle exec rake
+      run: bundle exec rake spec
+
+  lint:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+    - name: Set up Ruby
+      uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: 3.1
+        bundler-cache: true # runs 'bundle install' and caches installed gems automatically
+
+    - name: Run linting with RuboCop
+      run: bundle exec rake rubocop