fix getRelativePosition type definition (#9610)

* fix getRelativePosition type definition

* Update helpers.dom.d.ts

Co-authored-by: Jukka Kurkela <jukka.kurkela@gmail.com>

types/helpers/helpers.dom.d.ts

@@ -1,6 +1,8 @@
+import { ChartEvent } from '../index.esm';
+
 export function getMaximumSize(node: HTMLElement, width?: number, height?: number, aspectRatio?: number): { width: number, height: number };
 export function getRelativePosition(
-	evt: MouseEvent,
+	evt: MouseEvent | ChartEvent,
 	chart: { readonly canvas: HTMLCanvasElement }
 ): { x: number; y: number };
 export function getStyle(el: HTMLElement, property: string): string;