Request for Help with POST
**Describe the bug**
This is a request for help rather than a bug report
**Expected behavior**
I have a working POST url that it control's Reolink camera's embeded siren. 

**To Reproduce**
Steps to reproduce the behavior:
This is my working POST url. 
`curl -X POST 'http://192.168.177.211/cgi-bin/api.cgi?user=admin&password=mypassword' -d '[{"cmd":"AudioAlarmPlay","action": 0, "param": {"alarm_mode": "times", "manual_switch": 1, "times": 3, "channel": 0}}]'`

**Version** (output of `npm list -g homebridge homebridge-http-switch`)
 - homebridge: 1.6.0
 - homebridge-http-switch: v0.5.36

**Configuration**
This is my configuration so far: 

```
{
    "accessory": "HTTP-SWITCH",
    "name": "Reolink Siren",
    "switchType": "stateless",
    "timeout": 3000,
    "debug": true,
    "onUrl": {
        "url": "http://192.168.177.211/cgi-bin/api.cgi?user=admin&password=mypassword",
        "method": "POST",
        "headers": {
            "Content-Type": "application/json"
        },
        "body": {
            "cmd": "AudioAlarmPlay",
            "action": 0,
            "param": {
                "alarm_mode": "times",
                "manual_switch": 1,
                "times": 3,
                "channel": 0
            }
        }
    }
}
```

```
Unfortunately, the plugin does not trigger the siren with the above configuration. Any ideas?