ci: make coverage upload step non-blocking by adding continue-on-error flag

Author: github-actions[bot]

.github/workflows/ci.yml

@@ -80,6 +80,7 @@ jobs:
         with:
           name: coverage
           path: coverage
+        continue-on-error: true
       - name: Upload to Codecov
         uses: codecov/codecov-action@015f24e6818733317a2da2edd6290ab26238649a
         with: