add codecov token

Author: shikokuchuo

.github/workflows/test-coverage.yaml

@@ -13,6 +13,7 @@ jobs:
     runs-on: ubuntu-latest
     env:
       GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
+      CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
 
     steps:
       - uses: actions/checkout@v4