REF: Avoid/defer `dtype=object` containers in plotting
Probably best to avoid operations on containers with these types unless needed/expected
pandas/plotting/_matplotlib/boxplot.py:246: error: Argument "labels" to "_set_ticklabels" has incompatible type "list[Hashable]"; expected "list[str]"  [arg-type]
 Seems benign thanks @mroeschke 