Always return a str when using hv.Dimension.pprint_value

[hoxbro]

Fixes #5378

[codecov-commenter]

Codecov Report

Merging #5383 (0d34c0b) into master (ad59a3f) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #5383   +/-   ##
=======================================
  Coverage   88.07%   88.07%           
=======================================
  Files         301      301           
  Lines       61965    61969    +4     
=======================================
+ Hits        54575    54579    +4     
  Misses       7390     7390           

Impacted Files	Coverage Δ
holoviews/core/dimension.py	86.42% <100.00%> (ø)
holoviews/tests/core/test_dimensions.py	99.53% <100.00%> (+<0.01%)	⬆️

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[philippjfr]

Looks good!