Update PHPCS Composer plugin dependency (#79)

Composer: update PHPCS Composer plugin dependency

Author: schlessera

composer.json

@@ -11,7 +11,7 @@
     "require": {
         "php": ">=5.4",
         "behat/behat": "^2.5",
-        "dealerdirect/phpcodesniffer-composer-installer": "^0.4.3 || ^0.5",
+        "dealerdirect/phpcodesniffer-composer-installer": "^0.4.3 || ^0.5 || ^0.6",
         "jakub-onderka/php-console-highlighter": "^0.4",
         "jakub-onderka/php-parallel-lint": "^1.0",
         "phpcompatibility/php-compatibility": "^9",