added github_token, because that's what the error message said to do,…

… but not sure why I have to https://docs.github.com/en/actions/security-for-github-actions/security-guides/automatic-token-authentication

.github/workflows/testing.yml

@@ -60,3 +60,4 @@ jobs:
       run: coveralls
       env:
         COVERALLS_REPO_TOKEN: ${{ secrets.COVERALLS_REPO_TOKEN }}
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}