Allow installation on PHP 8

Author: kukulich

composer.json

@@ -9,7 +9,7 @@
 		"bin-dir": "bin"
 	},
 	"require": {
-		"php": "^7.1",
+		"php": "^7.1 || ^8.0",
 		"dealerdirect/phpcodesniffer-composer-installer": "^0.6.2 || ^0.7",
 		"phpstan/phpdoc-parser": "0.4.5 - 0.4.9",
 		"squizlabs/php_codesniffer": "^3.5.5"