Add rarity to set

public/data/honkai3rd/stigmata-sets/otto-apocalypse.json

@@ -9,5 +9,6 @@
   "threeSetSkill": {
     "name": "Spear of Sky 3 Pieces",
     "description": "Charges once every 5s. The next charged attack adds a Sky Brand to the target. The Sky Brand explodes after a 0.5s delay, dealing 80% ATK of Lightning DMG to nearby enemies."
-  }
-}
+  },
+  "rarity": 5
+}