chore(deps): update codecov/codecov-action action to v6 (#691)

Author: renovate[bot]

.github/workflows/_tests.yaml

@@ -73,7 +73,7 @@ jobs:
             matrix.python-version == '3.14' &&
             env.CODECOV_TOKEN != ''
           }}
-        uses: codecov/codecov-action@v5
+        uses: codecov/codecov-action@v6
         with:
           token: ${{ env.CODECOV_TOKEN }}
           files: coverage-integration.xml