Clarify new password error message

"Your password has not changed" might imply there was an error changing your password, rather than you didn't change it

user_management/api/serializers.py

@@ -105,7 +105,7 @@ def validate_new_password2(self, attrs, source):
 
     def validate(self, attrs):
         if attrs.get('old_password') == attrs.get('new_password'):
-            msg = _('Your password has not changed.')
+            msg = _('Your new password must not be the same as your old password.')
             raise serializers.ValidationError({'new_password': msg})
         return attrs