fix: ensure URL is imported for node.js < v10 (#4)

The WHATWG-compatible `URL` class was added in Node.js v6.13.0/v7.0.0,
but was not made a global until v10.0.0. By explicitly importing it from
the `url` module we can support older versions of Node.js.

rollup.config.js

@@ -11,7 +11,7 @@ export default {
     format: "cjs",
     sourcemap: true,
   },
-  external: ["events", "inquirer", "puppeteer"],
+  external: ["events", "inquirer", "puppeteer", "url"],
   plugins: [sourcemaps(), babel(), addShebang({ include: outputFile })],
   watch: {
     clearScreen: false,

src/index.ts

@@ -2,6 +2,7 @@ import EventEmitter from "events";
 import type TypedEmitter from "typed-emitter";
 import inquirer from "inquirer";
 import puppeteer, { Browser, Request, Page } from "puppeteer";
+import { URL } from "url"; // not added to `global` until Node.js v10
 
 /**
  * If we’re being run directly and not imported as a package then call the