Work around breaking changes in upload-artefact.

See <actions/upload-artifact#602>.

Author: ioquatix

.github/workflows/test-coverage.yaml

@@ -35,6 +35,8 @@ jobs:
       run: bundle exec bake test
 
     - uses: actions/upload-artifact@v4
+      include-hidden-files: true
+      if-no-files-found: error
       with:
         name: coverage-${{matrix.os}}-${{matrix.ruby}}
         path: .covered.db