fix: remove hasOwnProperty workaround

vue-test-utils-next now uses jest v27.1+, which includes a fix for hasOwnPropery (see jestjs/jest#11721).
This allows to remove the dirty workaround we had in our codebase, but users will have to update to Jest v27.1+.

package.json

@@ -50,7 +50,13 @@
     "vuex": "^4.0.2"
   },
   "peerDependencies": {
-    "vue": "^3.0.1"
+    "vue": "^3.0.1",
+    "jest": "^27.1.0"
+  },
+  "peerDependenciesMeta": {
+    "jest": {
+      "optional": true
+    }
   },
   "author": {
     "name": "Lachlan Miller",

src/mount.ts

@@ -464,10 +464,6 @@ export function mount(
   // if not, use the return value from app.mount.
   const appRef = vm.$refs[MOUNT_COMPONENT_REF] as ComponentPublicInstance
   const $vm = Reflect.ownKeys(appRef).length ? appRef : vm
-  // we add `hasOwnProperty` so jest can spy on the proxied vm without throwing
-  $vm.hasOwnProperty = (property) => {
-    return Reflect.has($vm, property)
-  }
   console.warn = warnSave
   return createWrapper(app, $vm, setProps)
 }