Use ruby/setup-ruby since actions/ruby is deprecated (#855)

.github/workflows/ci.yml

@@ -14,29 +14,22 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        ruby: ['2.4.x', '2.5.x', '2.6.x']
+        ruby: ['2.4', '2.5', '2.6']
 
     steps:
       - name: Checkout
         uses: actions/checkout@v1
 
       - name: Setup Ruby
-        uses: actions/setup-ruby@v1
+        uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
 
       - name: Install sqlite
         run: |
           sudo apt-get install libsqlite3-dev
 
-      - name: Update System
-        run: |
-          gem update --system --no-document
-
-      - name: Bundle install for Annotate models
-        run: |
-          bundle install --jobs=4 --retry=3
-
       - name: Run Tests
         run: INTEGRATION_TESTS=1 bundle exec rspec