Use better caching strategy (#11)

.github/workflows/ci.yml

@@ -5,21 +5,30 @@ on: push
 jobs:
   test:
     runs-on: ubuntu-latest
+    env:
+      BUNDLE_PATH: vendor/bundle
     strategy:
       matrix:
         ruby: [3.0, 3.3]
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4
 
+      - name: Restore cache
+        uses: actions/cache@v4
+        with:
+          key: gems
+          path: |
+            gemfiles
+            vendor/bundle
+
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with:
-          bundler-cache: true
           ruby-version: ${{ matrix.ruby }}
 
       - name: Install dependencies
-        run: bundle && cd spec/dummy && bundle && cd ../.. && bundle exec appraisal install
+        run: bundle && bundle exec appraisal install
 
       - name: Run tests
         run: bundle exec appraisal bin/check