Add PHPUnit 12 support (#24)

Author: keradus

composer.json

@@ -11,7 +11,7 @@
     ],
     "require": {
         "php": "^7.0 || ^8.0",
-        "phpunit/phpunit": "^6.5.14 || ^7.5.20 || ^8.5.41 || ^9.6.22 || ^10.5.45 || ^11.5.7"
+        "phpunit/phpunit": "^6.5.14 || ^7.5.20 || ^8.5.41 || ^9.6.22 || ^10.5.45 || ^11.5.7 || ^12.0.2"
     },
     "autoload": {
         "psr-4": {