Update composer.json

Author: Krzysztof Grzelak

composer.json

@@ -2,7 +2,7 @@
     "name": "simpaypl/simpay",
     "description": "Official SimPay API",
     "type": "library",
-    "version": "1.5",
+    "version": "1.6",
     "license": "MIT",
     "minimum-stability": "stable",
     "require": {