Update versioning

[cnweaver]

Description

Drop support for python 3.7 and use importlib instead of setuptools to get package versions. importlib.metadata was 'provisional' in 3.8 and 3.9, but given that it was then made non-provisional without substantial changes in 3.10, this seems safe enough.

Checklist

• [ ] All new functions and classes are documented and adhere to Google doc style (3.8.3-3.8.6 of this document)
• [ ] Add/update sphinx documentation with any relevant changes.
• [ ] Add/update pytest-style tests in /tests, ensuring sufficient code coverage.
• make test runs without errors.
• make lint doesn't give any warnings.
• make format doesn't give any code formatting suggestions.
• make doc runs without errors and generated docs render correctly.
• Check that CI pipeline run on this PR passes all stages.
• Review signoff by at least one developer.

Resolves #215

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.85%. Comparing base (ca3fff4) to head (3e31419).
Report is 8 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #219   +/-   ##
=======================================
  Coverage   99.85%   99.85%           
=======================================
  Files          15       15           
  Lines        1335     1367   +32     
=======================================
+ Hits         1333     1365   +32     
  Misses          2        2           

Flag	Coverage Δ
pytest	99.85% <100.00%> (+<0.01%)	⬆️

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[adambrazier]

All good, we should keep an eye on Python 3,13 over the medium term