升级到 babel 的新版本

Hi! When building the current version of async (3.2.6) from source, I get several warnings about security issues in outdated packages. One potential way to address this is to use babel 7.x and `@rollup/plugin-node-resolve` instead. I have changed what is needed to get it to build on Debian (which no longer has some of the Node.js packages listed in `package.json`), and the diff is below. I'm not submitting it as a PR yet, as it will certainly also need changes to the `package.json` file and possibly elsewhere, but I could do so if you wished.