feat: add Violin trace type #218

Job	Run time
semver	1m 3s
Rustfmt	13s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	4m 25s
Clippy	5m 36s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 19s
Code Coverage	17s
Build Book	3m 58s
Build Wasm Examples (callback-example)	1m 1s
Build Examples (custom_controls)	37s
Build Examples (ndarray)	32s
Build Examples (shapes)	35s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	3m 27s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	7m 34s
Build Examples (3d_charts)	34s
Build Examples (themes)	36s
Build Examples (customization/consistent_static_format_export)	1m 41s
Build Examples (kaleido)	1m 28s
Build Examples (subplots)	35s
Build Examples (scientific_charts)	32s
Build Examples (customization/multiple_plots_example)	36s
Build Wasm Examples (basic)	58s
Build Examples (basic_charts)	34s
Build Examples (maps)	42s
Build Examples (financial_charts)	37s
Build Examples (customization/density_mapbox_example)	34s
Build Examples (statistical_charts)	37s
Build Examples (images)	55s
	43m 36s

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