Speed up rubocop execution

.github/workflows/ci.yml

@@ -99,4 +99,4 @@ jobs:
           bundler-cache: true
 
       - name: Run rubocop
-        run: bundle exec rubocop
+        run: bundle exec rubocop --parallel

.rubocop.yml

@@ -22,3 +22,8 @@ AllCops:
     - 'bin/*'
     - 'db/schema.rb'
     - 'vendor/**/*'
+    # Ignore local files for faster processing
+    - 'tmp/**/*'
+    - 'out/**/*'
+    - 'node_modules/**/*'
+    - 'coverage/**/*'