security gas masks give pepperspray immunity again (#94155)

## About The Pull Request

when tgstation was doing the weird gas mask nerf thing, the security
hailer mask was caught in the crossfire as a compromise for not being
FOV restricted. now that FOV restrictions have been removed though, it
still hasn't gotten its immunity back. this pr readds the secmask pepper
spray immunity, while it's pulled over your mouth and nose of course
## Why It's Good For The Game

both pepper-spray and the sechailer are underused. pepperspray is
usually discarded or ignored, and most sec players use the security gas
mask like a normal breath mask. pepperspray is cool and criminally
underused because the server lagging will make you stun yourself, which
is very odd because generally security officers have immunity to all of
their own non-baton non-disabler tools (flash, flashbang, pepperspray
before the mask was nerfed)

## Changelog
🆑
balance: the security gas mask is pepper-proof again.
/🆑

code/modules/clothing/masks/hailer.dm

@@ -54,7 +54,7 @@ GLOBAL_LIST_INIT(hailer_phrases, list(
 	visor_flags = BLOCK_GAS_SMOKE_EFFECT | MASKINTERNALS
 	visor_flags_inv = HIDEFACIALHAIR | HIDEFACE | HIDESNOUT
 	flags_cover = MASKCOVERSMOUTH
-	visor_flags_cover = MASKCOVERSMOUTH
+	visor_flags_cover = MASKCOVERSMOUTH | PEPPERPROOF
 	tint = 0
 	fishing_modifier = 0
 	unique_death = 'sound/items/sec_hailer/sec_death.ogg'