utilities: plotting: axisbg is deprecated
utilities: plotting: axisbg is deprecated

https://matplotlib.org/api/prev_api_changes/api_changes_2.0.0.html

Signed-off-by: Liam Beguin <ac8b122174024ef5e58ca7d6d989651e9bbfc948@gmail.com>

wdm0006/git-pandas,wdm0006/git-pandas