Update php-amqplib organization

php-amqplib has changed maintainers and changed the organization it is under.

Author: postalservice14

php/composer.json

@@ -1,5 +1,5 @@
 {
     "require": {
-        "videlalvaro/php-amqplib": "v2.1.0"
+        "php-amqplib/php-amqplib": "v2.6.1"
     }
-}
+}