Add more old PHP versions

Author: jochensengier

composer.json

@@ -17,7 +17,7 @@
         }
     ],
     "require": {
-        "php": "^5.4 || ^7.0 || ^7.1 || ^7.2 || ^7.3 || ^7.4 || ^8.0 || ^8.1",
+        "php": "^5.4 || ^5.5 || ^5.6 || ^7.0 || ^7.1 || ^7.2 || ^7.3 || ^7.4 || ^8.0 || ^8.1",
         "guzzlehttp/guzzle": "^5.0 || ^6.0 || ^7.0"
     },
     "autoload": {