Update to use project Django Json Field

papertrail/fields.py

@@ -1,7 +1,7 @@
 # Attempt to use the built-in PostgreSQL json field, but if that is not
 # available try the 3rd party jsonfield one.
 try:
-    from django.contrib.postgres.fields import JSONField as BaseJSONField
+    from django.db.models import JSONField as BaseJSONField
 except ImportError:
     from jsonfield.fields import JSONField as BaseJSONField