Fix manual publish option to skip publish to PyPA

[ketozhang]

Broken, because the if condition I had didn't work as intended. Now you can toggle on to disable and off to enable publish to PyPA.

See example, the publish stage should be skipped (not failure)
https://github.com/ketozhang/MulensModel/actions/runs/8871760998

[rpoleski]

Thanks.
Do you know how to setup codecov or similar action? It was working for years and recently started stating that there is 0% coverage of all files and producing some error messages. After a few tries correcting it, I gave up. If possible, I'd like to have something that tells what is the coverage of modified code for a pull request.

[ketozhang]

Yeah we can take a look---set up coverage to show up on PR. Related to #65.

[rpoleski]

I've already forgotten about #65, the list might be outdated. My current approach is to have 100% (except plotting and some unexpected values) coverage of code that is added.
I removed codecov in 8af13bc, you may find failed codecov runs based on the date, if that is helpful.