Replace numpy.asscalar() with numpy.ndarray.item()

[jwodder]

asscalar() has been deprecated since numpy 1.16, with numpy.ndarray.item() recommended instead. Moreover, it was completely removed in numpy 1.23, released June 22. Note that none of our tests seem to cover the case where an NWB has any probe_ids.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.41%. Comparing base (50ca7b0) to head (b70707e).
Report is 1023 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1056      +/-   ##
==========================================
- Coverage   88.41%   88.41%   -0.01%     
==========================================
  Files          72       72              
  Lines        9251     9250       -1     
==========================================
- Hits         8179     8178       -1     
  Misses       1072     1072              

Flag	Coverage Δ
unittests	88.41% <ø> (-0.01%)	⬇️

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[yarikoptic]

Note that none of our tests seem to cover the case where an NWB has any probe_ids.

and due to if within list comprehension we did not even know about that through coverage. Oh well, let's just proceed for now. Thank you @jwodder ! I will mark for release so people with new numpy do not experience crashes etc.

[github-actions]

🚀 PR was released in 0.45.0 🚀