Upgrade warning and set stacklevel to first file outside holoviews

[hoxbro]

The warning will now emit a FutureWarning in a notebook.

I found a way to determine the first stack level outside holoviews, hopefully making it easier to understand.

[codecov-commenter]

Codecov Report

Merging #5472 (cf29f56) into master (8b84839) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5472      +/-   ##
==========================================
- Coverage   88.12%   88.11%   -0.02%     
==========================================
  Files         301      302       +1     
  Lines       62201    62216      +15     
==========================================
+ Hits        54817    54823       +6     
- Misses       7384     7393       +9     

Impacted Files	Coverage Δ
holoviews/core/data/pandas.py	93.37% <100.00%> (-0.10%)	⬇️
holoviews/util/_exception.py	100.00% <100.00%> (ø)
holoviews/plotting/bokeh/styles.py	91.57% <0.00%> (-1.06%)	⬇️
holoviews/plotting/plotly/callbacks.py	93.98% <0.00%> (-0.93%)	⬇️
holoviews/plotting/mpl/element.py	89.94% <0.00%> (-0.14%)	⬇️
holoviews/core/options.py	82.34% <0.00%> (-0.11%)	⬇️
holoviews/tests/test_streams.py	98.33% <0.00%> (-0.11%)	⬇️
holoviews/plotting/plot.py	92.84% <0.00%> (-0.09%)	⬇️
holoviews/operation/datashader.py	83.89% <0.00%> (-0.09%)	⬇️
holoviews/plotting/bokeh/element.py	88.81% <0.00%> (-0.07%)	⬇️
... and 1 more

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[jlstevens]

Happy to see this merged!

[github-actions]

This pull request has been automatically locked since there has not been any recent activity after it was closed. Please open a new issue for related bugs.