okay, try the stretch builds

Author: ahayworth

.github/workflows/main.yml

@@ -51,7 +51,7 @@ jobs:
       - name: Checkout code
         uses: actions/checkout@v1
       - name: Build container
-        run: docker build . --file Dockerfile --tag octocatalog-diff:ruby${{matrix.ruby-version}} --build-arg RUBY_VERSION=${{matrix.ruby-version}}
+        run: docker build . --file Dockerfile --tag octocatalog-diff:ruby${{matrix.ruby-version}} --build-arg RUBY_VERSION=${{matrix.ruby-version}}-stretch
       - name: Tests
         run: docker run -e PUPPET_VERSION -e PUPPET_VERSIONS -e RSPEC_TEST -e RUBOCOP_TEST -e COVERAGE octocatalog-diff:ruby${{matrix.ruby-version}} /app/script/cibuild
       - name: Rubocop