[NO GBP] megaphone tts actually works now. (#85031)

## About The Pull Request
At some point, I've added the spam check to the PR, without thinking the
var was being set by other comsig proc runs before the TTS one.

## Why It's Good For The Game
I WANNA BE LOUD AND FUNNY!

## Changelog

🆑
fix: fixed megaphone tts filter.
/🆑

code/game/objects/items/devices/megaphone.dm

@@ -35,7 +35,6 @@
 		to_chat(user, span_warning("\The [src] needs to recharge!"))
 	else
 		playsound(loc, 'sound/items/megaphone.ogg', 100, FALSE, TRUE)
-		spamcheck = world.time + 5 SECONDS
 		speech_args[SPEECH_SPANS] |= voicespan
 
 /obj/item/megaphone/proc/add_tts_filter(mob/living/carbon/user, list/message_args)
@@ -44,6 +43,7 @@
 		return
 	if(spamcheck > world.time)
 		return
+	spamcheck = world.time + 5 SECONDS
 	if(obj_flags & EMAGGED)
 		///somewhat compressed and ear-grating, crusty and noisy with a bit of echo.
 		message_args[TREAT_TTS_FILTER_ARG] += "acrusher=samples=9:level_out=7,aecho=delays=100:decays=0.4,aemphasis=type=emi,crystalizer=i=6,acontrast=60,rubberband=pitch=0.9"