Add alpha to plt.colorbar when using pyplot.contourf

[billetd]

Scope

This is a really small change to fix the alpha in the map potential colour bar. The mappable object created for the colour bar doesn't preserve the alpha used when using plt.contourf(). This change adds it in.

Current behaviour:

Fixed behaviour:

issue:

Approval

1

Test

import pydarn
import matplotlib.pyplot as plt
import datetime as dt

mapfile = '20221130.n.map'
SDarn_read = pydarn.SuperDARNRead(mapfile)
map_data = SDarn_read.read_map()
record = dt.datetime(2022, 11, 30, 15, 0)
pydarn.Maps.plot_mapdata(map_data, start_time=record, lowlat=50, coastline=True, contour_fill=True, color_vectors=False)