Use setup-ruby action

Author: manicmaniac

.github/workflows/test.yml

@@ -49,6 +49,12 @@ jobs:
     - uses: actions/checkout@v2
     - name: Modify Cartfile.resolved
       run: sed -i '' -E '/apollographql\/apollo-ios/s/"[0-9.]+"/"${{ matrix.apollo }}"/' Cartfile.resolved
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: 2.6
+        bundler-cache: true
+      env:
+        BUNDLE_WITHOUT: development:documentation
     - uses: actions/cache@v2
       id: cache-carthage-build
       with:
@@ -60,10 +66,6 @@ jobs:
         carthage checkout
         ( cd Carthage/Checkouts/apollo-ios && swift package resolve ) # Workaround for Carthage's timeout error while reading xcodeproj.
         carthage build --platform '${{ matrix.platform }}' --cache-builds --use-xcframeworks --no-use-binaries
-    - name: Install Ruby dependencies
-      run: bundle install
-      env:
-        BUNDLE_WITHOUT: development:documentation
     - name: Run unit tests
       run: xcodebuild test -project ApolloDeveloperKit.xcodeproj -scheme ApolloDeveloperKit -sdk '${{ matrix.sdk }}' -destination '${{ matrix.destination }}' | xcpretty
     - name: Collect coverages
@@ -88,8 +90,10 @@ jobs:
     runs-on: macOS-10.15
     steps:
     - uses: actions/checkout@v2
-    - name: Install dependencies
-      run: bundle install
+    - uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: 2.6
+        bundler-cache: true
       env:
         BUNDLE_WITHOUT: documentation:test
     - name: Lint podspec