Fix database keyword quote problem on migration v161 (#17523)

* support rerun migration v161

Author: lunny

models/migrations/v161.go

@@ -5,6 +5,8 @@
 package migrations
 
 import (
+	"context"
+
 	"xorm.io/xorm"
 )
 
@@ -40,8 +42,17 @@ func convertTaskTypeToString(x *xorm.Engine) error {
 		return err
 	}
 
+	// to keep the migration could be rerun
+	exist, err := x.Dialect().IsColumnExist(x.DB(), context.Background(), "hook_task", "type")
+	if err != nil {
+		return err
+	}
+	if !exist {
+		return nil
+	}
+
 	for i, s := range hookTaskTypes {
-		if _, err := x.Exec("UPDATE hook_task set typ = ? where type=?", s, i); err != nil {
+		if _, err := x.Exec("UPDATE hook_task set typ = ? where `type`=?", s, i); err != nil {
 			return err
 		}
 	}