Fail on Codecov failure, and use token to fix upload

Author: adamtheturtle

.github/workflows/ci.yml

@@ -51,3 +51,6 @@ jobs:
 
       - name: "Upload coverage to Codecov"
         uses: "codecov/codecov-action@v4"
+        with:
+          fail_ci_if_error: true
+          token: ${{ secrets.CODECOV_TOKEN }}