skip coverage upload on contributors repositories

[hduelme]

@filiphr as a follow up of #248 I disabled the coverage upload to Codecov.
Step skipped in contributors repositories https://github.com/hduelme/mapstruct-idea/actions/runs/20558714613/job/59046427179, but still run on PR https://github.com/mapstruct/mapstruct-idea/actions/runs/20558771239/job/59046546343?pr=252

The changes made in #248 on Codecov can be reverted.

[filiphr]

Thanks @hduelme. I don't think that it runs on PRs now. There are only 7 checks now, vs the 8 before. The codecov check is missing

[hduelme]

@filiphr For this PR the step is not skipped. There was a upload https://app.codecov.io/gh/mapstruct/mapstruct-idea/tree/hduelme%2Fmapstruct-idea%3Askip-coverage-upload-on-contributors-repositories)](https://app.codecov.io/gh/mapstruct/mapstruct-idea/tree/hduelme%2Fmapstruct-idea%3Askip-coverage-upload-on-contributors-repositories

VS

[filiphr]

You are right @hduelme. I was looking for the check, but maybe there is anyways no check reported if there is no change. The upload is correct. Thanks