Update composer.json

Author: AlaaSarhan

composer.json

@@ -18,10 +18,10 @@
     },
     "minimum-stability": "stable",
     "require": {
-        "php": "^5.6|^7.0|^8.0"
+        "php": "^7.1|^8.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^5.7|^6.0|^8.0|^9.0",
+        "phpunit/phpunit": "^7.0|^8.0|^9.0",
         "squizlabs/php_codesniffer": "^2.3|^3.0"
     },
     "scripts": {