[Bug] After upgrade to 1.5.2 `addMembership EADDRINUSE`; root cause => getNetworkInterface()
Hi Alex,
first of all, thanks for the great work.

**Describe the bug**
I upgraded to the latest version and I am facing the issue that I get now `addMembership EADDRINUSE` error. I set the networkInterface in my config.json but it doesn't work.

I had a deeper look into the changes and I found the followed commit.
https://github.com/alexryd/homebridge-shelly/commit/d88cbcd3312459517f2a8e41f0c5ed160750f135

https://github.com/alexryd/homebridge-shelly/blob/d88cbcd3312459517f2a8e41f0c5ed160750f135/platform.js#L90

The issue is that you are looping through the interfaces and expect in the array the property address but in my case the method os.networkInterfaces() returns something as followed:

```js
{ lo: [
        { address: '127.0.0.1',
       netmask: '255.0.0.0',
       family: 'IPv4',
       mac: '00: 00: 00: 00: 00: 00',
       internal: true,
       cidr: '127.0.0.1/8'
        },
        { address: ': : 1',
       netmask: 'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff',
       family: 'IPv6',
       mac: '00: 00: 00: 00: 00: 00',
       scopeid: 0,
       internal: true,
       cidr: ': : 1/128'
        }
    ],
  enxXxxxxx: [
        { address: '192.168.178.24',
       netmask: '255.255.255.0',
       family: 'IPv4',
       mac: 'xxxx',
       internal: false,
       cidr: '192.168.178.24/24'
        },
        ...
    }]
}
```

So in that case it doesn't match the networkInterface. In my case the followed code would work and match the IP.

```js
for (const i in ifaces) {
    ifaces[i].forEach(element => {
        if (element.address === '192.168.178.24') {
            //address found, so it's valid       
            console.log(element.address)
            return element.address
        }
    });
}
```

Another quickfix would be, you change the followed line to `return iface`. 
https://github.com/alexryd/homebridge-shelly/blob/d88cbcd3312459517f2a8e41f0c5ed160750f135/platform.js#L111

The warning would be shown int the log, but it would work like in the previous versions, if I'm not mistaken.

If you want I can also contribute and create a PR.

**Environment:**
 - Plugin version: 0.15.2
 - Device running homebridge: Raspberry Pi
