chore: only upload coverage artifacts on PR runs

Add github.event_name == 'pull_request' condition to artifact upload
to avoid creating unnecessary artifacts on non-PR pushes.

Author: eablack

.github/workflows/ci.yml

@@ -34,7 +34,7 @@ jobs:
       - name: unit tests
         run: npm test
       - name: Upload coverage reports
-        if: always() && matrix.os == 'ubuntu-latest' && matrix.node-version == '22.x'
+        if: always() && github.event_name == 'pull_request' && matrix.os == 'ubuntu-latest' && matrix.node-version == '22.x'
         uses: actions/upload-artifact@v4
         with:
           name: coverage-report