Run tests on PHP 8.4 (#19)

Author: GromNaN

.github/workflows/phpunit.yml

@@ -12,7 +12,7 @@ jobs:
 
     strategy:
       matrix:
-        php: [8.1, 8.2, 8.3]
+        php: [8.1, 8.2, 8.3, 8.4]
         extension: [":bcmath", ":gmp"]
 
     name: PHP ${{ matrix.php }}