Declare Symfony 7.x support

Author: JoryHogeveen

composer.json

@@ -23,8 +23,8 @@
 	"require": {
 		"php": ">=8.1",
 		"phpoffice/phpspreadsheet": "^1.16",
-		"symfony/serializer": "^6.0",
-		"symfony/filesystem": "^6.0"
+		"symfony/serializer": "^6.0|^7.0",
+		"symfony/filesystem": "^6.0|^7.0"
     },
     "require-dev": {
 		"symfony/test-pack": "^1.0"