Mac OS X上的XAMPP SSL问题

Question

I have XAMPP installed on Mac OS X and am having an issue running this code

<?php
    echo file_get_contents("https://extensions.bolt.cm/list.json");
?>

I get the following error

Warning: file_get_contents(): SSL operation failed with code 1. OpenSSL Error messages: error:14090086:SSL routines:SSL3_GET_SERVER_CERTIFICATE:certificate verify failed in index.php on line 2

mod_ssl is loaded and OpenSSL is enabled

allow_url_fopen and allow_url_include are both on

I have seen other threads talk about uncommenting the extension=php_openssl.dll line in the php.ini file, but that appears to be for Windows. If there is something similar I am supposed to do on OS X, I would appreciate the advice.

Any help would be greatly appreciated!

Update

Here are the results to the code that Alexander suggested running

bool(false)
string(69) "SSL certificate problem: self signed certificate in certificate chain"
string(0) ""