Make item pickle smaller

[jsignell]

Related Issue(s):

• Pickled items / ItemCollections are large pystac-client#315

Description:

Not totally sure if this is a good idea, but I figured a PR would be a good place to hash that out. The only limitation I can see is that if you have a resolved target object on your link, it will not be resolved with you roundtrip it to pickle and back.

PR Checklist:

• pre-commit hooks pass locally
• Tests pass (run scripts/test)
• Documentation has been updated to reflect changes, if applicable
• 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 ✅

Comparison is base (c5a79c7) 91.11% compared to head (156ae44) 91.12%.
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1285      +/-   ##
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+ Coverage   91.11%   91.12%   +0.01%     
==========================================
  Files          51       51              
  Lines        6986     6994       +8     
  Branches      999     1001       +2     
==========================================
+ Hits         6365     6373       +8     
  Misses        444      444              
  Partials      177      177              

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[gadomski]

The only limitation I can see is that if you have a resolved target object on your link, it will not be resolved with you roundtrip it to pickle and back.

This feels like the right behavior -- you (theoretically) can always re-resolve the object later. I'm ok with this change, but I'm not the target user here -- is there anyone that uses pystac in Dask-land that can verify that things are better w/ this fix. Maybe @TomAugspurger?

[TomAugspurger]

Won't have time to test this out for real, but in general I've found len(pickle.dumps(obj)) to be a good enough test for fixes like this.