Cache remote JSON schemas

[avbentem]

This caches remote JSON schemas for repeated use. Closes #142.

The value 128 in @lru_cache(maxsize=128) is actually the default, so just added to be explicit that it's not an endless cache.

[geospatial-jeff]

LGTM, downside of functools.lru_cache is no TTL but extension schemas change infrequently enough I can't imagine this will be a problem. I'm imagining, for example, a long-lived fastapi service that is using stac-pydantic.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.02%. Comparing base (a927d25) to head (03f0873).
Report is 56 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #155      +/-   ##
==========================================
- Coverage   96.59%   96.02%   -0.57%     
==========================================
  Files          25       25              
  Lines         587      579       -8     
==========================================
- Hits          567      556      -11     
- Misses         20       23       +3     

Flag	Coverage Δ
unittests	96.02% <100.00%> (-0.57%)	⬇️

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.

[vincentsarago]

thanks @avbentem 🙏