build: 不要なcomposerパッケージが削除できていない問題の修正

Author: uidev1116

composer.json

@@ -11,7 +11,7 @@
     "google/apiclient": "^2.14"
   },
   "scripts": {
-    "post-update-cmd": "Google_Task_Composer::cleanup"
+    "pre-autoload-dump": "Google\\Task\\Composer::cleanup"
   },
   "extra": {
     "google/apiclient-services": [