Allow Symfony 6 packages (#30)

Co-authored-by: Jon Green <[email protected]>

Author: jontjs

composer.json

@@ -16,9 +16,9 @@
   ],
   "require": {
     "php": ">=7.0",
-    "symfony/console": "~3.4 || ~4.0 || ~5.0",
-    "symfony/dotenv": "~3.4 || ~4.0 || ~5.0",
-    "symfony/process": "~3.4 || ~4.0 || ~5.0",
+    "symfony/console": "~3.4 || ~4.0 || ~5.0 || ~6.0",
+    "symfony/dotenv": "~3.4 || ~4.0 || ~5.0 || ~6.0",
+    "symfony/process": "~3.4 || ~4.0 || ~5.0 || ~6.0",
     "jackiedo/dotenv-editor": "~1.0"
   },
   "autoload": {