Bump version in module

This is mostly so I can install from Git for minfraud and get 4.0.0.

Author: oschwald

geoip2/__init__.py

@@ -1,7 +1,7 @@
 # pylint:disable=C0111
 
 __title__ = "geoip2"
-__version__ = "3.0.0"
+__version__ = "4.0.0"
 __author__ = "Gregory Oschwald"
 __license__ = "Apache License, Version 2.0"
 __copyright__ = "Copyright (c) 2013-2020 Maxmind, Inc."