upgrade to upload-artifact@v4

Author: yngrtc

.github/workflows/grcov.yml

@@ -75,7 +75,7 @@ jobs:
               --service-name "GitHub Actions" \
               --service-number ${{ github.run_id }}
       - name: Upload coverage as artifact
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: lcov.info
           # path: ${{ steps.grcov.outputs.report }}