Update post install and update cmds

Author: frozzare

composer.json

@@ -25,8 +25,8 @@
     "wp-coding-standards/wpcs": "dev-develop"
   },
   "scripts": {
-    "post-install-cmd": "\"vendor/bin/phpcs\" --config-set installed_paths vendor/wp-coding-standards/wpcs",
-    "post-update-cmd" : "\"vendor/bin/phpcs\" --config-set installed_paths vendor/wp-coding-standards/wpcs"
+    "post-install-cmd": "if [ -f vendor/bin/phpcs ]; then \"vendor/bin/phpcs\" --config-set installed_paths vendor/wp-coding-standards/wpcs; fi",
+    "post-update-cmd": "if [ -f vendor/bin/phpcs ]; then \"vendor/bin/phpcs\" --config-set installed_paths vendor/wp-coding-standards/wpcs; fi"
   },
   "minimum-stability": "dev",
   "prefer-stable": true