Revert "fix(options): use beforeUnmount instead of unmounted"

This reverts commit 9726e0a.

Author: Akryum

packages/vue-apollo-option/src/mixin.js

@@ -145,6 +145,6 @@ export function installMixin (app, provider) {
 
     created: launch,
 
-    beforeUnmount: destroy,
+    unmounted: destroy,
   })
 }