Update `geoip2` and `maxmind-db` versions

[andsel]

New versions of geoip2 and maxmind-db were releases.
The maxmind-db 3.1.1 comes with an NPE fix related to #226.

Update both dependencies to the latest.

Related:

• NullPointerException (NPE) happening with version 7.3.0 #226 (comment)