Switch to KGB

[Raphael Hertzog <hertzog@debian.org>]

Hello,

the irker bot that we were using for IRC notifications has been down for a
while so I switched all our repositories to use KGB (I used the script
from https://salsa.debian.org/pkg-security-team/pkg-security-team).

I updated the team's wiki page accordingly.

Thanks to Unit193 for the suggestion/poke.

Cheers,
-- 
  ⢀⣴⠾⠻⢶⣦⠀   Raphaël Hertzog <hertzog@debian.org>
  ⣾⠁⢠⠒⠀⣿⡁
  ⢿⡄⠘⠷⠚⠋    The Debian Handbook: https://debian-handbook.info/get/
  ⠈⠳⣄⠀⠀⠀⠀   Debian Long Term Support: https://deb.li/LTS