Support ipywidgets>=8.0

[philippjfr]

Fixes #3778

[codecov]

Codecov Report

Merging #3782 (6f630bb) into master (4de525f) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #3782      +/-   ##
==========================================
- Coverage   83.33%   83.33%   -0.01%     
==========================================
  Files         217      217              
  Lines       31631    31632       +1     
==========================================
  Hits        26361    26361              
- Misses       5270     5271       +1     

Flag	Coverage Δ
ui-tests	33.77% <0.00%> (+<0.01%)	⬆️
unitexamples-tests	76.24% <0.00%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
panel/pane/ipywidget.py	48.88% <0.00%> (-1.12%)	⬇️

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