[bug] geolite2 missing from requirements

[nemesifier]

It seems to me that this package: https://github.com/RR2DO2/maxminddb-geolite2, it's being referenced here:
https://github.com/django-getpaid/django-plans/blob/master/plans/utils.py#L3

But the package is not in the dependencies defined in setup.py, hence if that code is triggered it fails unless the package is installed.

Is maxminddb-geolite2 a hard dependency or should we make this optional and avoid this failure if the package is not installed?