fix(types): metaInfo should always be a member function

In `vue-class-component`, if the defined function is not a member function, it is treated as a data property.
Even if you register a custom hook via `Component.registerHooks`, it will not work.

types/vue.d.ts

@@ -13,6 +13,6 @@ declare module "vue/types/options" {
 
 declare module "vue/types/vue" {
   interface Vue {
-    metaInfo?: MetaInfo | (() => MetaInfo)
+    metaInfo(): MetaInfo
   }
 }