fix: fall back to epsg in crs_string, too

[gadomski]

Description:

Hopefully this, with #1509, will fix our backwards-compatability 🤞🏼 . We didn't catch this previously because our other proj v1.1 item had a proj:wkt set.

PR Checklist:

• Pre-commit hooks and tests pass (run scripts/test)
• This PR maintains or improves overall codebase code coverage.
• Changes are added to the CHANGELOG. See the docs for information about adding to the changelog.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.47%. Comparing base (21a0bbb) to head (5ebee47).
Report is 28 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1510   +/-   ##
=======================================
  Coverage   91.47%   91.47%           
=======================================
  Files          54       54           
  Lines        7520     7522    +2     
  Branches      910      911    +1     
=======================================
+ Hits         6879     6881    +2     
  Misses        457      457           
  Partials      184      184           

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