Fix logo plotting issue when colorbar is added

[kevindougherty-noaa]

The following code outputs a figure of 3D 2m temperature. When adding a colorbar, a second logo is plotted.

grid1 = MapGridded(latitude=lat3d,
                   longitude=lon3d,
                   data=arr3d)
grid1.cmap = 'cividis'

plot1 = CreatePlot()
plot1.plot_layers = [grid1]
plot1.projection = 'plcarr'
plot1.domain = 'global'
plot1.add_map_features(['coastline', 'states'])
plot1.add_colorbar()

fig = CreateFigure()
fig.plot_list = [plot1]
fig.create_figure()
fig.tight_layout()
fig.plot_logo(loc='bottom right', zoom=0.9, alpha=0.5)

Most likely this is because when plotting logos, it looks for all axes to plot on them. Colorbars are created as a new axis, so need to figure out how to handle this better.