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

Author: renovate[bot]

.github/workflows/tests.yaml

@@ -15,6 +15,6 @@ jobs:
       - run: uv run ./bin/lint
       - run: uv run ./bin/test
       - name: Upload coverage reports to Codecov
-        uses: codecov/codecov-action@75cd11691c0faa626561e295848008c8a7dddffe # v5
+        uses: codecov/codecov-action@57e3a136b779b570ffcdbf80b3bdc90e7fab3de2 # v6
         env:
           CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}