Switch to setuptools_scm for version management

[jeromekelleher]

Closes #421

[codecov-commenter]

Codecov Report

❌ Patch coverage is 60.00000% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.50%. Comparing base (5802a84) to head (503f134).

Files with missing lines	Patch %	Lines
pyslim/_version.py	60.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #423      +/-   ##
==========================================
- Coverage   96.74%   96.50%   -0.25%     
==========================================
  Files           8        8              
  Lines         769      773       +4     
  Branches      146      146              
==========================================
+ Hits          744      746       +2     
- Misses         15       17       +2     
  Partials       10       10              

Flag	Coverage Δ
python-tests	96.50% <60.00%> (-0.25%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[jeromekelleher]

Can you have a look please and merge it you're happy @petrelharp?