Drop python2 support, add py38 and py39

[ikamensh]

Hi, I'd like to use this library on py38 and higher. Since py2 and py35 are outdated, I have removed them and applied some automatic refactorings for newer python. All refactorings were done with tools (pyupgrade, flynt) so should be low risk. Test testit.py passes.

[kloczek]

It would be good to merge that change and make new release.

[ddurham2]

pretty please.. pull this and push a release to pypi

[kata198]

Sorry for late reply, I am retired. Can we do this in a way that does not lose python2 support? I am not willing to lose that. Perhaps the .format function? That should work for both 2 and 38.

[ddurham2]

If you're using your own pip package, could you not just lock to a specific version in your application's requirements.txt/setup.py (e.g. func_timeout==4.3.5)?

[kata198]

Yeah you could. If you are using artifactory or whatever the new deal is, you can just publish a version 4.3.6 with your own changes, and it would always fetch that.

I'm not sure if you are asking me to do something, but some very important systems I developed use this lib, and I no longer work at the agencies that do in order to update their requirements.txt file. I imagine a lot of other code I didn't even write is in the same predicament. If you just change all the f"blah %{variable}" to use str.format instead, I can publish that and not break anyone whilst supporting new deployments. I no longer own a computer to make.these changes myself.