ci: remove code.json, update scripts, fix release workflow

[wpbonelli]

Fixes for the release automation after discussion with @jdhughes-usgs

• don't version code.json, just generate when needed (and update update_version.py)
• add retries for metadata file gen in release.yml (USGS endpoints are unreliable)
• fix autocommit/pr contents: version.txt, pymake/config.py, and README.md

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70.051%. Comparing base (006b6ba) to head (ced4a26).

Additional details and impacted files

@@              Coverage Diff              @@
##           develop      #190       +/-   ##
=============================================
- Coverage   77.946%   70.051%   -7.895%     
=============================================
  Files           20        20               
  Lines         3496      3496               
=============================================
- Hits          2725      2449      -276     
- Misses         771      1047      +276     

see 11 files with indirect coverage changes