comp(matplotlib): Add compatibility with Matplotlib 3.9

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 70.49180% with 18 lines in your changes missing coverage. Please review.

Project coverage is 88.49%. Comparing base (e5f7aed) to head (e3e951d).

Files	Patch %	Lines
...s/tests/plotting/matplotlib/test_annotationplot.py	76.66%	7 Missing :warning:
holoviews/plotting/mpl/chart.py	37.50%	5 Missing :warning:
holoviews/plotting/mpl/stats.py	70.00%	3 Missing :warning:
...views/tests/plotting/matplotlib/test_violinplot.py	71.42%	2 Missing :warning:
...views/tests/plotting/matplotlib/test_boxwhisker.py	75.00%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #6307 +/- ## ========================================== - Coverage 88.52% 88.49% -0.04% ========================================== Files 323 323 Lines 67999 68031 +32 ========================================== + Hits 60196 60202 +6 - Misses 7803 7829 +26 ```

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