Fixes announcements font scaling (#78995)

## About The Pull Request

Creates CSS spans for priority announcement and minor announcement so
they scale properly with the player's chosen font size


![image](https://github.com/tgstation/tgstation/assets/83487515/0706891d-05e9-4f00-b24f-ebf37efdd18d)

## Why It's Good For The Game

Fixes https://github.com/tgstation/tgstation/issues/78875

## Changelog

🆑 LT3
fix: Fixed font scaling for announcements
/🆑

code/controllers/subsystem/ticker.dm

@@ -285,7 +285,7 @@ SUBSYSTEM_DEF(ticker)
 		to_chat(world, span_notice("and..."))
 		for(var/holidayname in GLOB.holidays)
 			var/datum/holiday/holiday = GLOB.holidays[holidayname]
-			to_chat(world, "<h4>[holiday.greet()]</h4>")
+			to_chat(world, span_info(holiday.greet()))
 
 	PostSetup()