fix(core): typing of key in VNodeProps (#4242)

close #4240

packages/runtime-core/src/vnode.ts

@@ -90,7 +90,7 @@ export type VNodeHook =
 
 // https://github.com/microsoft/TypeScript/issues/33099
 export type VNodeProps = {
-  key?: string | number
+  key?: string | number | symbol
   ref?: VNodeRef
 
   // vnode hooks
@@ -138,7 +138,7 @@ export interface VNode<
 
   type: VNodeTypes
   props: (VNodeProps & ExtraProps) | null
-  key: string | number | null
+  key: string | number | symbol | null
   ref: VNodeNormalizedRef | null
   /**
    * SFC only. This is assigned on vnode creation using currentScopeId