Allow newer version of symfony filesystem (#30)

Refs #28

Author: shadowhand

composer.json

@@ -10,7 +10,7 @@
     ],
     "require": {
         "php": "^7.4 || ^8.0",
-        "symfony/filesystem": "^4.2 || ^5.0",
+        "symfony/filesystem": "^4.2 || ^5.0 || ^6.0",
         "psr/log": "^1.0 || ^2.0 || ^3.0"
     },
     "require-dev": {