Set Leveling#getLeaderboard optional parameters as optional (#5)

* Set Leveling#getLeaderboard optional parameters as optional

* I lied, now lint should pass

Author: OIRNOIR

src/handlers/Leveling.ts

@@ -2,11 +2,7 @@ import type { Leaderboard, LevelData, SuccessResponse } from "../types"
 import { BaseHandler } from "./BaseHandler"
 
 export class Leveling extends BaseHandler {
-	async getLeaderboard(
-		guildId: string,
-		start: number | undefined,
-		end: number | undefined
-	) {
+	async getLeaderboard(guildId: string, start?: number, end?: number) {
 		if (start !== undefined && start < 0) {
 			throw new Error("Start parameter must be non-negative")
 		}