ci.yml in prometheus_exporter-0.7.0

- old
+ new
@@ -10,27 +10,33 @@
   build:
     runs-on: ubuntu-latest
     name: Ruby ${{ matrix.ruby }}
     strategy:
       matrix:
-        ruby: ["2.7", "2.6", "2.5", "2.4"]
+        ruby: ["2.7", "2.6", "2.5"]
     steps:
       - uses: actions/checkout@master
         with:
           fetch-depth: 1
       - uses: actions/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}
       - uses: actions/cache@v2
         with:
           path: vendor/bundle
-          key: ${{ runner.os }}-${{ matrix.ruby }}-gems-${{ hashFiles('**/Gemfile.lock') }}
+          key: ${{ runner.os }}-${{ matrix.ruby }}-gems-v2-${{ hashFiles('**/Gemfile.lock') }}
           restore-keys: |
-            ${{ runner.os }}-${{ matrix.ruby }}-gems-
+            ${{ runner.os }}-${{ matrix.ruby }}-gems-v2-
       - name: Setup gems
         run: |
+          gem install bundler
+          # for Ruby <= 2.6 , details https://github.com/rubygems/rubygems/issues/3284
+          gem update --system 3.0.8 && gem update --system
           bundle config path vendor/bundle
           bundle install --jobs 4
+          bundle exec appraisal install
       - name: Rubocop
         run: bundle exec rubocop
+      - name: install gems
+        run: bundle exec appraisal bundle
       - name: Run tests
-        run: bundle exec rake
+        run: bundle exec appraisal rake