Switch WKT to use type over class name.

[eseglem]

What I am changing

• Make the _wkt_type function work when the class is inherited from.

How I did it

• Switched the _wkt_type function to use the type. Since a "type" MUST exist in the spec, and it cannot be modified. It will always match the WKT type unlike the class name.

How you can test it

• Tests still run properly. And now this works:

from geojson_pydantic import Point
class PointType(Point):
    ...

print(PointType(coordinates=[123, 123]).wkt)
# POINT (123.0 123.0)

Related Issues

• Fixes: Problem with "wkt" method. #78

[geospatial-jeff]

LGTM