Upgrade support to php 8

Author: misarji

composer.json

@@ -24,11 +24,11 @@
         "sort-packages": true
     },
     "require": {
-        "php": "^5.6 || ^7.0",
-        "squizlabs/php_codesniffer": "^2.6"
+        "php": "^7.0 || ^8.0",
+        "squizlabs/php_codesniffer": "^3.6"
     },
     "require-dev": {
         "php-coveralls/php-coveralls": "^1.0",
-        "phpunit/phpunit": "^5.5"
+        "phpunit/phpunit": ">=6.5"
     }
 }