Switch to codecov action

[mikehardy]

The codecov npmjs.com package is fully deprecated https://www.npmjs.com/package/codecov

The codecov upload is failing in CI at this point, indicating it is not working anymore for some reason: https://github.com/invertase/react-native-firebase/runs/5666297808?check_suite_focus=true#step:22:45

It could be that it is a problem with generating results etc but staying on deprecated software is not the way to go

Need to switch to this: https://github.com/marketplace/actions/codecov

[stale[bot]]

Hello 👋, to help manage issues we automatically close stale issues. This issue has been automatically marked as stale because it has not had activity for quite some time. Has this issue been fixed, or does it still require the community's attention?

This issue will be closed in 15 days if no further activity occurs. Thank you for your contributions.

[github-actions[bot]]

Hello 👋, to help manage issues we automatically close stale issues.

This issue has been automatically marked as stale because it has not had activity for quite some time.Has this issue been fixed, or does it still require attention?

This issue will be closed in 15 days if no further activity occurs.

Thank you for your contributions.

[mikehardy]

Did this at some point