RBY: Move Articuno to UUBL (smogon#10440)

https://www.smogon.com/forums/threads/rby-uu-articuno-voting.3747617/#post-10201454

Author: shrianshChari

data/mods/gen1/formats-data.ts

@@ -429,7 +429,7 @@ export const FormatsData: import('../../../sim/dex-species').ModdedSpeciesFormat
 		tier: "OU",
 	},
 	articuno: {
-		tier: "UU",
+		tier: "UUBL",
 	},
 	zapdos: {
 		tier: "OU",