Allows Hardliner captains vest to hold firearms (#3920)

## About The Pull Request

As is the title, allows the captains vest of Hardliners to holster
firearms on the back

## Why It's Good For The Game

Due to the evil and fucked up future the Hardliners captains vest comes
from,

![image](https://github.com/user-attachments/assets/84594f54-78b3-4aaa-8c20-253a0193d06b)
it couldn't hold firearms unlike literally every other captains vest

## Changelog

:cl:
balance: The Hardliners captain jacket can hold firearms now
/:cl:

code/modules/clothing/factions/hardliners.dm

@@ -102,6 +102,10 @@
 	armor = list("melee" = 35, "bullet" = 35, "laser" = 35, "energy" = 40, "bomb" = 25, "bio" = 0, "rad" = 0, "fire" = 50, "acid" = 50)
 	togglename = "buttons"
 
+/obj/item/clothing/suit/toggle/armor/vest/hardliners/Initialize()
+	. = ..()
+	allowed = GLOB.security_vest_allowed
+
 ///////////////
 //Spacesuits//
 //////////////