Update composer.json

Author: Mike Zukowsky

composer.json

@@ -2,7 +2,7 @@
   "name": "mikemix/tactician-module",
   "description": "ZF2 Module to use the League of Extraordinary Packages' Tactician library - flexible command bus implementation",
   "require": {
-    "php": "^5.5 || ^7.0",
+    "php": "^5.6 || ^7.0",
     "league/tactician": "^1.0",
     "zendframework/zend-mvc": "^3.0",
     "zendframework/zend-servicemanager": "^3.0"