[Bug]: remove parameter authkey

[xopez]

User story

As an admin, I want to remove the start parameter "authkey"

Game

gmodserver

Linux distro

Ubuntu 22.04

Command

command: start

Further information

The console at the server start says that the parameter can be safely removed.
I am using the branch x86-64. Hence I can't say if this output will be the same for the stable branch.

If it can be removed, the default parameter and the docs need to be updated.

Relevant log output

-authkey is no longer required by Garry's Mod. You can safely remove it from your server's launch options.

Steps to reproduce

1. install gmodserver
2. Change lgsm config to branch="x86-64"
3. Update the server
4. Start server
5. Take a look to the console

[xopez]

I think its not a real bug, cause the parameter will just be ignored and the server starts normally

[xopez]

Tested with stable branch, it can also be removed