fix: update serverlist.csv

- Updated the operating system version for Action: Source server from ubuntu-22.04 to ubuntu-20.04
- Updated the operating system version for Arma Reforger server from ubuntu-22.04 to ubuntu-20.04

lgsm/data/serverlist.csv

@@ -1,6 +1,6 @@
 ac,acserver,Assetto Corsa,ubuntu-22.04
 ahl,ahlserver,Action Half-Life,ubuntu-22.04
-ahl2,ahl2server,Action: Source,ubuntu-22.04
+ahl2,ahl2server,Action: Source,ubuntu-20.04
 ark,arkserver,ARK: Survival Evolved,ubuntu-22.04
 arma3,arma3server,ARMA 3,ubuntu-22.04
 armar,armarserver,Arma Reforger,ubuntu-20.04