y-axis spine z-order too low in plot_evoked #13492
Description
The GFP curve in mne.viz.plot_evoked is plotted above the y-axis spine. But that is not limited to the GFP-only case, the channels are also plotted above the y-axis in other evoked plots.
I guess we just need to adjust the zorder of the axis spines.
Originally posted by @mistraube in #13481 (comment)