COMPAT: Bokeh 3.6 and add minimal test for Bokeh 3.5

[hoxbro]

Also, some temporary workarounds for bokeh-fastapi and bokeh/label/rc.

[codecov]

Codecov Report

Attention: Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.

Project coverage is 82.20%. Comparing base (260da79) to head (9ed71c9).
Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
panel/tests/ui/widgets/test_tabulator.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7322      +/-   ##
==========================================
- Coverage   82.21%   82.20%   -0.01%     
==========================================
  Files         337      337              
  Lines       50498    50503       +5     
==========================================
+ Hits        41516    41517       +1     
- Misses       8982     8986       +4     

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