Upgrade flask-appbuilder to latest. (#6030)

* Upgrade flask-appbuilder to latest.

* Skip constraint deletes if not exist.

* Document breaking change in flask-login.

superset/views/utils.py

@@ -30,7 +30,7 @@ def bootstrap_user_data(username=None, include_perms=False):
         'firstName': user.first_name,
         'lastName': user.last_name,
         'userId': user.id,
-        'isActive': user.is_active(),
+        'isActive': user.is_active,
         'createdOn': user.created_on.isoformat(),
         'email': user.email,
     }