Add rubocop with a todo list

.github/workflows/ci.yml

@@ -20,4 +20,17 @@ jobs:
       - name: Install dependencies
         run: bundle install
       - name: Run tests
-        run: bundle exec rspec spec/
+        run: bundle exec rake spec
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.4"
+          bundler-cache: true
+      - name: Install dependencies
+        run: bundle install
+      - name: Run tests
+        run: bundle exec rake rubocop

.rubocop.yml

@@ -0,0 +1,4 @@
+inherit_from: .rubocop_todo.yml
+
+AllCops:
+  NewCops: enable