Coverage reports fail to upload, leading to "failure" of unit tests

[PGijsbers]

Even when unit tests pass, the workflow fails as coverage gives the error "rate limit reached": https://github.com/openml-labs/gama/actions/runs/9513702560/job/26224349537?pr=215#step:3:408

Probably an issue with the tokens:

[2024-06-14T09:16:14.707Z] ['info'] -> No token specified or token is empty