PROJ_DATA to replace PROJ_LIB environment variable

[vincentsarago]

https://github.com/OSGeo/PROJ/pull/3253

[jcary741]

I was able to get around this using this at the top of my handler file:

import pyproj
pyproj.datadir.set_data_dir(os.path.join(os.path.dirname(__file__), 'share/proj'))