Bump codecov/codecov-action from 5.5.3 to 6.0.0

Bumps [codecov/codecov-action](https://github.com/codecov/codecov-action) from 5.5.3 to 6.0.0.
- [Release notes](https://github.com/codecov/codecov-action/releases)
- [Changelog](https://github.com/codecov/codecov-action/blob/main/CHANGELOG.md)
- [Commits](codecov/codecov-action@v5.5.3...v6.0.0)

---
updated-dependencies:
- dependency-name: codecov/codecov-action
  dependency-version: 6.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/tests.yaml

@@ -63,7 +63,7 @@ jobs:
           uv run coverage combine coverage*/.coverage*
           uv run coverage xml -i
       - name: 🚀 Upload coverage report
-        uses: codecov/codecov-action@v5.5.3
+        uses: codecov/codecov-action@v6.0.0
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           fail_ci_if_error: true