Allow newer phpunit versions

Author: williamdes

.gitignore

@@ -5,3 +5,4 @@ composer.phar
 .buildpath
 .project
 .settings
+.phpunit.result.cache

composer.json

@@ -27,7 +27,7 @@
         "mustangostang/spyc": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.5.8",
+        "phpunit/phpunit": "^8.5.8 || ^9 || ^10 || ^11",
         "psr/cache": "^1.0.1",
         "psr/simple-cache": "^1.0.1",
         "matthiasmullie/scrapbook": "^1.4.7",