Issue 155: single source of version, setuptools -> flit

[jpreszler]

This should resolve issue #155 , but I couldn't get setuptools to do dynamic versioning because of the imports in __init__.py. Switching to flit seems to work with minimal changes.

I tested by changing the version locally and using pip install -e . in a clean environment. The version was correct. Also using python -m build produced targ.gz and whl files with the correct versions in names.

Not sure if other testing would be good or if there's further discussion needed before changing the backend build system.

[codecov]

Codecov Report

Merging #239 (33209e2) into main (133b987) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #239   +/-   ##
=======================================
  Coverage   73.89%   73.89%           
=======================================
  Files          19       19           
  Lines        1149     1149           
=======================================
  Hits          849      849           
  Misses        300      300           

[drbenvincent]

Just checking that this is still a draft PR? When it's ready can you get me and @lucianopaz to review?

[jpreszler]

@drbenvincent and @lucianopaz , I've cleaned this up and it's ready for review.

I looked into bump2version but it seemed like it would involve more changes because it's an external command line tool, but would work if there's strong desire to keep setuptools as the build system.