Removed the php version check. (#5850)

Author: limingxinleo

tests/AstTest.php

@@ -127,10 +127,6 @@ function __construct(?\HyperfTest\Di\Stub\Foo $foo)
 
     public function testAstProxyForEnum()
     {
-        if (PHP_VERSION_ID < 80100) {
-            $this->markTestSkipped('The version below 8.1 does not support enum.');
-        }
-
         $ast = new Ast();
         $code = $ast->proxy(FooEnumStruct::class);
 

tests/Stub/FooEnum.php

@@ -11,9 +11,7 @@
  */
 namespace HyperfTest\Di\Stub;
 
-if (PHP_VERSION_ID > 80100) {
-    enum FooEnum: int
-    {
-        case DEFAULT = 1;
-    }
+enum FooEnum: int
+{
+    case DEFAULT = 1;
 }