chore: bump codecov-action to v6

Author: xfgong

.github/workflows/ci.yml

@@ -32,7 +32,7 @@ jobs:
 
       - name: Upload coverage to Codecov
         if: matrix.python-version == '3.13'
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@v6
         with:
           files: coverage.xml
           token: ${{ secrets.CODECOV_TOKEN }}