Register default backends when restoring state

[alkment]

This allows the schema to be defined outside the function called in parallel

[alkment]

Fixes #1541

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.03%. Comparing base (4df61da) to head (6feb801).
Report is 49 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1550       +/-   ##
===========================================
- Coverage   94.29%   83.03%   -11.26%     
===========================================
  Files          91      111       +20     
  Lines        7024     8186     +1162     
===========================================
+ Hits         6623     6797      +174     
- Misses        401     1389      +988     

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[cosmicBboy]

Thanks @alkment, and congrats on your first PR to pandera! 🚀