Try test-bundler-parallel in GitHub Actions

.github/workflows/macos.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: macos-latest
     strategy:
       matrix:
-        test_task: [ "check", "test-bundler", "test-bundled-gems", "leaked-globals" ]
+        test_task: [ "check", "test-bundler-parallel", "test-bundled-gems", "leaked-globals" ]
       fail-fast: false
     env:
       GITPULLOPTIONS: --no-tags origin ${{github.ref}}

.github/workflows/ubuntu.yml

@@ -4,11 +4,11 @@ jobs:
   make:
     strategy:
       matrix:
-        test_task: [ "check", "test-bundler", "test-bundled-gems", "test-all TESTS=--repeat-count=2", "leaked-globals" ]
+        test_task: [ "check", "test-bundler-parallel", "test-bundled-gems", "test-all TESTS=--repeat-count=2", "leaked-globals" ]
         os: [ubuntu-latest, ubuntu-16.04]
         debug: ["", "-DRUBY_DEBUG"]
         exclude:
-          - test_task: test-bundler
+          - test_task: test-bundler-parallel
             os: ubuntu-16.04
           - test_task: test-bundled-gems
             os: ubuntu-16.04