ENH: MatplotlibDeprecationWarning: is_first_col function was deprecated
Fix for [#40714](https://github.com/pandas-dev/pandas/issues/40714)

The is_first_col function was deprecated in Matplotlib 3.4 and will be removed two minor releases later. Used ax.get_subplotspec().is_first_col() instead.



closing in favor of #40718  thanks @arnaujc91 this is a bit tricky as have multiple versions of mpl to support