Use tagged api-clients/middleware-json

Author: WyriHaximus

composer.json

@@ -16,7 +16,7 @@
     "api-clients/resource": "^3.0",
     "api-clients/transport": "dev-master",
     "api-clients/middleware-user-agent": "^1.0",
-    "api-clients/middleware-json": "dev-master"
+    "api-clients/middleware-json": "^1.0"
   },
   "require-dev": {
     "api-clients/resource-generator": "dev-master",