update composer.json

Author: freyo

composer.json

@@ -4,7 +4,8 @@
     "keywords": ["laravel-queue", "cmq", "qcloud"],
     "require": {
         "php": ">=5.6.4",
-        "illuminate/queue": "5.2.*|5.3.*|5.4.*|5.5.*|5.6.*|5.7.*|5.8.*"
+        "illuminate/queue": "5.2.*|5.3.*|5.4.*|5.5.*|5.6.*|5.7.*|5.8.*",
+        "ext-json": "*"
     },
     "require-dev": {
         "php": ">=5.6.4",