Removed reference to spatialreference.org being a Django website.

spatialreference.org has been redesigned, possibly in 2023 [1], and no longer uses Django, see repo [2].

[1] https://spatialreference.org/about.html
[2] https://github.com/OSGeo/spatialreference.org

Author: smithdc1

docs/ref/contrib/gis/model-api.txt

@@ -159,8 +159,7 @@ calculations.
 
 Additional Resources:
 
-* `spatialreference.org`__: A Django-powered database of spatial reference
-  systems.
+* `spatialreference.org`__: A database of spatial reference systems.
 * `The State Plane Coordinate System`__: A website covering the various
   projection systems used in the United States. Much of the U.S. spatial
   data encountered will be in one of these coordinate systems rather than