Improve Turn config
Adding a denied peers list protects from the usage of the turnserver as a proxy:
denied-peer-ip=
- 0.0.0.0-0.255.255.255
- 10.0.0.0-10.255.255.255
- 100.64.0.0-100.127.255.255
- 127.0.0.0-127.255.255.255
- 169.254.0.0-169.254.255.255
- 172.16.0.0-172.31.255.255
- 192.0.0.0-192.0.0.255
- 192.0.2.0-192.0.2.255
- 192.88.99.0-192.88.99.255
- 192.168.0.0-192.168.255.255
- 198.18.0.0-198.19.255.255
- 198.51.100.0-198.51.100.255
- 203.0.113.0-203.0.113.255
- 240.0.0.0-255.255.255.255
https://github.com/coturn/coturn/security/advisories/GHSA-6g6j-r9rf-cm7p