Fix out-of-transaction query in removeOrgUser (#4521) (#4524)

Author: SagePtr

models/org.go

@@ -454,7 +454,7 @@ func AddOrgUser(orgID, uid int64) error {
 func removeOrgUser(sess *xorm.Session, orgID, userID int64) error {
 	ou := new(OrgUser)
 
-	has, err := x.
+	has, err := sess.
 		Where("uid=?", userID).
 		And("org_id=?", orgID).
 		Get(ou)