Added new 'srtext' spatialite 4.x SpatialRefSys column to its model.

This is for general consistency in the GeoDjango DB backends.
Thanks Claude for the fix.

Refs #19678.

django/contrib/gis/db/backends/spatialite/models.py

@@ -1,7 +1,7 @@
 """
  The GeometryColumns and SpatialRefSys models for the SpatiaLite backend.
 """
-from django.db import models
+from django.db import connection, models
 from django.contrib.gis.db.backends.base import SpatialRefSysMixin
 from django.utils.encoding import python_2_unicode_compatible
 
@@ -53,9 +53,13 @@ class SpatialRefSys(models.Model, SpatialRefSysMixin):
     auth_srid = models.IntegerField()
     ref_sys_name = models.CharField(max_length=256)
     proj4text = models.CharField(max_length=2048)
+    if connection.ops.spatial_version[0] >= 4:
+        srtext = models.CharField(max_length=2048)
 
     @property
     def wkt(self):
+        if hasattr(self, 'srtext'):
+            return self.srtext
         from django.contrib.gis.gdal import SpatialReference
         return SpatialReference(self.proj4text).wkt