Fix support for pynwb v3 which has changed API slightly

[jwodder]

Closes #1582.

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 88.66%. Comparing base (e87941e) to head (4439a1d).
Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
dandi/pynwb_utils.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1584      +/-   ##
==========================================
+ Coverage   88.59%   88.66%   +0.06%     
==========================================
  Files          78       78              
  Lines       10855    10857       +2     
==========================================
+ Hits         9617     9626       +9     
+ Misses       1238     1231       -7     

Flag	Coverage Δ
unittests	88.66% <75.00%> (+0.06%)	⬆️

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[yarikoptic]

Thank you @jwodder , let's proceed with release to get it addressed for the users.

[github-actions]

🚀 PR was released in 0.67.0 🚀