Pickle save for VIPosterior

[manuelgloeckler]

Will work for any default flow and VIPosterior input

• For custom distributions, it might fail if the object is not pickable
• For custom distributions, the build_fn is gone after saving -> Local unpickable function currently; maybe change that;
• Add tests

[manuelgloeckler]

Blocked by PyRight #848 .

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (2830fda) 76.02% compared to head (ccac2bc) 76.09%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
sbi/inference/posteriors/vi_posterior.py	96.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #951      +/-   ##
==========================================
+ Coverage   76.02%   76.09%   +0.06%     
==========================================
  Files          80       80              
  Lines        6319     6341      +22     
==========================================
+ Hits         4804     4825      +21     
- Misses       1515     1516       +1     

Flag	Coverage Δ
unittests	76.09% <97.14%> (+0.06%)	⬆️

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[manuelgloeckler]

Here is a small summary about what was changed

VIPosterior pickle support

To make the VIPosterior pickable and deepcopy compatible, unpickable files must be removed and manually rebuilt.

• To support pickle on has to override __setstate__ (rebuilding removed stuff) and __getstate__ (removing unpickable stuff).
• The __deepcopy__ protocol uses this function by default. Necessary modifications to make it pickable, however, make it incompatible with deep copy (at least in some relevant cases, covered by tests). This requires overriding __deepcopy__.
• In addition to the deep copy tests, I added a pickle test (uses torch.save, and deletes it afterwards)

Pyright Fix

• Fixed all pyright errors (given current pyright version)
• Errors due to insufficient type information in external libraries is ignored using notype

[janfb]

Great, thanks for fixing this!! 👍

Just some documentation comments. feel free to merge once they are addressed.