Timeout on stateless switch does not work
**Describe the bug**
Using the timeout on a stateless switch does only work while the home app is open. Putting the home app into background immediately turns off the switch.

**Expected behavior**
The timeout should correctly work even if the home app is closed

**Version** (output of `npm list -g homebridge homebridge-http-switch`)
 - homebridge: 1.8.5
 - homebridge-http-switch: 0.5.36

**Configuration**
```json
        {
            "accessory": "HTTP-SWITCH",
            "name": "Kaffemaschine",
            "switchType": "stateless",
            "timeout": 1800000,
            "onUrl": "http://192.168.0.94/light/0?turn=off",
        }
```
