ci: explicitly specify token for codecov

Explicitly specify the codecov token to be used (i.e., `CODECOV_TOKEN`),
given that the latest v4 release of the codecov action requires it to be able to
generate coverage reports.

Additionally, fail CI if coverage reporting fails, since coverage is an important enough
metric for us to ensure that it's tracked consistently.


Signed-off-by: Anant Thazhemadam <47104651+thazhemadam@users.noreply.github.com>

.github/workflows/CI.yml

@@ -49,6 +49,8 @@ jobs:
  - uses: codecov/codecov-action@v4
  with:
  files: lcov.info
+ token: ${{ secrets.CODECOV_TOKEN }}
+ fail_ci_if_error: true
  docs:
  name: Documentation
  runs-on: ubuntu-latest