ci: add all-passed job to simplify pull request merge rules (#370)

Author: pkuczynski

.github/workflows/tests.yml

@@ -61,3 +61,11 @@ jobs:
           CC_TEST_REPORTER_ID: ${{ secrets.CC_TEST_REPORTER_ID }}
         with:
           coverageCommand: bundle exec appraisal rspec
+
+  all-passed:
+    runs-on: ubuntu-latest
+    if: always()
+    needs:
+      - test
+    steps:
+      - run: exit ${{ contains(needs.*.result, 'failure') && 1 || 0 }}