In transform.py, Use get_facecolor instead

`courses/bdml_fundamentals/demos/earthquakevm/transform.py`

FYI:

```
./transform.py
{'magnitude': 0.69, 'lat': 38.8016663, 'timestamp': '2019-08-03T04:49:39.810Z', 'lon': -122.8219986}
/usr/lib/python3/dist-packages/mpl_toolkits/basemap/__init__.py:1623: MatplotlibDeprecationWarning: The get_axis_bg
color function was deprecated in version 2.0. Use get_facecolor instead.
fill_color = ax.get_axis_bgcolor()
/usr/lib/python3/dist-packages/mpl_toolkits/basemap/__init__.py:3260: MatplotlibDeprecationWarning: The ishold func
tion was deprecated in version 2.0.
b = ax.ishold()
/usr/lib/python3/dist-packages/mpl_toolkits/basemap/__init__.py:3269: MatplotlibDeprecationWarning: axes.hold is de
precated.
See the API Changes document (http://matplotlib.org/api/api_changes.html)
for more details.
ax.hold(b)
```