Update show_versions to use package name

[hoxbro]

Changes in #6072 to no use importlib.metadata.version meant that we should use the package name and not the import name.

I also added a tsdownsample to the list.

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (6dc23ae) 88.65% compared to head (6c1c45d) 88.65%.

Files	Patch %	Lines
holoviews/util/_versions.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6081      +/-   ##
==========================================
- Coverage   88.65%   88.65%   -0.01%     
==========================================
  Files         314      314              
  Lines       65839    65841       +2     
==========================================
+ Hits        58370    58371       +1     
- Misses       7469     7470       +1     

Flag	Coverage Δ
ui-tests	23.67% <50.00%> (+<0.01%)	⬆️

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