vis: switch from pkg_resource to importlib_resources

[stewartboogert]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 3 lines in your changes missing coverage. Please review.

Project coverage is 70.31%. Comparing base (c746f0d) to head (4a3783d).
Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
src/pyg4ometry/visualisation/ViewerBase.py	0.00%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #186   +/-   ##
=======================================
  Coverage   70.31%   70.31%           
=======================================
  Files         152      152           
  Lines       23412    23412           
=======================================
  Hits        16462    16462           
  Misses       6950     6950           

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