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

Author: renovate[bot]

.github/workflows/test.yaml

@@ -15,7 +15,7 @@ jobs:
     - uses: actions/checkout@v6
     - run: make test-cover
     - name: Upload coverage reports to Codecov
-      uses: codecov/codecov-action@v5.5.3
+      uses: codecov/codecov-action@v6.0.0
       with:
         token: ${{ secrets.CODECOV_TOKEN }}
         slug: dnaeon/makefile-graph