Fixed the CLIP War Correspondent sprite for Vox (#3540)

## About The Pull Request

This helmet has a Vox sprite available that used to work (but doesn't
anymore for some reason), this PR makes it correctly show up now.

## Why It's Good For The Game

Fixes species support for an item that should have it.

## Changelog

:cl:
fix: War Correspondent helmet has a proper sprite for Vox. 
/:cl:

code/modules/clothing/factions/clip.dm

@@ -330,6 +330,8 @@
 	icon_state = "clip_m10_correspondant"
 	item_state = "clip_m10_correspondant"
 
+	supports_variations = VOX_VARIATION
+
 /obj/item/clothing/head/helmet/riot/clip
 	name = "\improper Minutemen riot helmet"
 	desc = "Designed to protect against close range attacks. Mainly used by the CMM-BARD against hostile xenofauna, it also sees prolific use on some Minutemen member worlds."