update antv G6 to v5

sample/workdir/sub/subtree1.json

@@ -5,7 +5,7 @@
   "firstid": 1,
   "group": [],
   "import": [],
-  "declvar": [],
+  "vars": [],
   "root": {
     "id": 1,
     "name": "Sequence",
@@ -27,4 +27,4 @@
       }
     ]
   }
-}
+}