Fix missing bom arg in d.ts

Author: ypresto

js-file-download.d.ts

@@ -2,6 +2,7 @@ declare module 'js-file-download' {
     export default function fileDownload(
         data: string | ArrayBuffer | ArrayBufferView | Blob,
         filename: string,
-        mime?: string
+        mime?: string,
+        bom?: string
     ): void;
 }