Switch from pkg_resources to packaging for parsing versions

[berquist]

Even after conda-forge/morfeus-ml-feedstock#7 I was still getting a CI failure and realized I've seen this problem before. See mu-editor/mu#2485 for a summary. It seems like adding setuptools to the recipe should have worked, but it is simply safer to switch to packaging. I think it has something to do with setuptools only being present in the build phase, not the run phase, but if you're just doing things locally in a venv, setuptools will still be present.

It makes more sense to me to add packaging as a runtime dependency than setuptools. After this, there would need to be a new release and the feedstock updated for both the new version and runtime dependency.