How to setup username and password for Turn Server in Docker Setup

I have been using the below command and config file for my docker setup. when I check the turn server URL, it works with any random username and password. How to setup a specific username and password for TURN server? Is there any way to set it directly in the docker command?

```
docker run -d --network=host \
-v $(pwd)/my.conf:/etc/coturn/turnserver.conf \
coturn/coturn
```

**Config file**
listening-port=3478
tls-listening-port=5349
fingerprint
lt-cred-mech
user=user1:pass1
syslog

Reproduce the docker run command with my.conf and verify how coturn loads lt-cred-mech and user=user1:pass1. Investigate why arbitrary credentials are accepted; done means the configured username and password are enforced, with the relevant behavior documented or fixed.

Written by the indexing model from the issue text.