chore(deps): update codecov/codecov-action action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -92,7 +92,7 @@ jobs:
             htmlcov/
             
       - name: Upload coverage to Codecov
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@v6
         with:
           file: ./coverage.xml
           flags: unittests