Ensure tasks are cancelled correctly

[philippjfr]

Fixes #7494

[codecov]

Codecov Report

Attention: Patch coverage is 95.23810% with 1 line in your changes missing coverage. Please review.

Project coverage is 86.73%. Comparing base (2c51805) to head (58a4272).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
panel/io/state.py	87.50%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7641      +/-   ##
==========================================
+ Coverage   86.25%   86.73%   +0.48%     
==========================================
  Files         346      346              
  Lines       52052    52066      +14     
==========================================
+ Hits        44897    45161     +264     
+ Misses       7155     6905     -250     

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