fix: multistream export cast

package-lock.json

@@ -1,6 +1,6 @@
 {
   "name": "nexe",
-  "version": "4.0.0-beta.1",
+  "version": "4.0.0-beta.2",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {

package.json

@@ -2,7 +2,7 @@
   "name": "nexe",
   "description": "Create a single executable out of your Node.js application",
   "license": "MIT",
-  "version": "4.0.0-beta.1",
+  "version": "4.0.0-beta.2",
   "contributors": [
     "Craig Condon <craig.j.condon@gmail.com> (http://crcn.io)",
     "Jared Allard <jaredallard@outlook.com>",

src/fs/bundle.ts

@@ -1,7 +1,7 @@
 import { stat as getStat, Stats, createReadStream } from 'fs'
 import { relative } from 'path'
 import { Readable } from 'stream'
-import combineStreams = require('multistream')
+import MultiStream = require('multistream')
 
 const stat = (file: string): Promise<Stats> => {
   return new Promise((resolve, reject) => {
@@ -61,7 +61,7 @@ export class Bundle {
   }
 
   toStream() {
-    return combineStreams(this.streams)
+    return new (MultiStream as any)(this.streams)
   }
 
   toJSON() {