fix:$token 参数隐式可空的参数修改为显式可空类型，以避免出现弃用警告或错误。

Author: Tinywan

src/JwtToken.php

@@ -174,7 +174,7 @@ public static function generateToken(array $extend): array
      * @throws JwtTokenException
      * @author Tinywan(ShaoBo Wan)
      */
-    public static function verify(int $tokenType = self::ACCESS_TOKEN, string $token = null): array
+    public static function verify(int $tokenType = self::ACCESS_TOKEN, ?string $token = null): array
     {
         $token = $token ?? self::getTokenFromHeaders();
         try {