Switch to esbuild?

I got a basic build working with esbuild via:

1. npm i esbuild
2. Add the following build script as `build.mjs`
```js
import esbuild from 'esbuild';
const { build } = esbuild;

build({
entryPoints: ['lib/index.ts'],
outdir: "dist",
sourcemap: "linked",
}).catch(() => process.exit(1));
```
3. run `node build.mjs`

This is advantageous because `esbuild` has 30x faster build times:

```sh
$ time npm run build > /dev/null

real 0m1.854s
user 0m2.890s
sys 0m0.111s

$ time node build.mjs

real 0m0.048s
user 0m0.032s
sys 0m0.016s
```