Handle WKT Extension Tag

EPSG.IO nowadays offers WKT for spatial reference systems that may contain an `EXTENSION` tag. 
This leads to parsing exceptions. A first step would be to quietly disregard it, but not fail.   
[see: stackoverflow](https://stackoverflow.com/questions/74306799/how-to-measure-distance-between-two-points-in-metres-with-nettopologysuite-pro)