Remove add-imaging-libs option from setup.py

[radarhere]

#8389 suggests removing add-imaging-libs from setup.py, as it is undocumented.

It was added in #3399 to allow use when building in AppVeyor. It is no longer used there.

It was also not included when #7171 made sure that other setup options would work with pip >= 23.3 (released October 16, 2023), so it no longer works with recent versions of pip.

[hugovk]

Tip: Co-authored-by can be used to give credit to the original author:

https://docs.github.com/en/pull-requests/committing-changes-to-your-project/creating-and-editing-commits/creating-a-commit-with-multiple-authors

Or even cherry pick if it's a clean commit.

[radarhere]

I attempted to cherry-pick, but it wasn't working for me. I do tend to forget about 'Co-authored-by', but thankfully, I was able to do that with 'Squash and merge'.