fix(pstbs): enable steammaster (#3722)

Author: h3o66

lgsm/config-default/config-lgsm/pstbsserver/_default.cfg

@@ -124,7 +124,7 @@ steamcmdforcewindows="no"
 branch=""
 betapassword=""
 # Master Server | https://docs.linuxgsm.com/steamcmd/steam-master-server
-steammaster="false"
+steammaster="true"
 
 ## Stop Mode | https://docs.linuxgsm.com/features/stop-mode
 # 1: tmux kill