build: Update codecov and use token

Update codecov to the latest version and start using the org-wide token for uploads.

See openedx/wg-frontend#179

Author: arbrandes

.github/workflows/ci.yml

@@ -34,4 +34,7 @@ jobs:
     - name: i18n_extract
       run: npm run i18n_extract
     - name: Coverage
-      uses: codecov/codecov-action@v3
+      uses: codecov/codecov-action@v4
+      with:
+        token: ${{ secrets.CODECOV_TOKEN }}
+        fail_ci_if_error: true