Mark as php 8.0 compatible

Author: itismadness

.github/workflows/test.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        php-version: ['7.2', '7.3', '7.4']
+        php-version: ['7.2', '7.3', '7.4', '8.0']
 
     steps:
     - uses: actions/checkout@v2

composer.json

@@ -15,7 +15,7 @@
         }
     },
     "require": {
-        "php": "^7.2"
+        "php": ">=7.2"
     },
     "require-dev": {
         "phpunit/phpunit": "^8",