Update composer for php-di

api/composer.json

@@ -10,7 +10,7 @@
     }
   ],
   "require-dev": {
-    "phpunit/phpunit": "5.7.9"
+    "phpunit/phpunit": "6.3.0"
   },
   "require": {
     "phpmailer/phpmailer": "^5.2",
@@ -18,6 +18,7 @@
     "php-http/guzzle6-adapter": "^1.1",
     "php-http/message": "^1.5",
     "php-http/curl-client": "^1.7",
-    "guzzlehttp/psr7": "^1.3"
+    "guzzlehttp/psr7": "^1.3",
+    "php-di/php-di": "4.4.10"
   }
 }