feat!: convert to es modules, drop node 10

[JustinBeckwith]

BREAKING CHANGE: this module now requires node.js 12 and above, and has moved to es modules by default.

[JustinBeckwith]

@bcoe this is super weird. Looks like everything works in node 14 and 16, but only on 12 I am getting:

> c8 mocha build/test


SyntaxError[ @/home/runner/work/linkinator/linkinator/build/test/test.cli.js ]: Unexpected token '?'
    at Loader.moduleStrategy (internal/modules/esm/translators.js:140:18)
----------|---------|----------|---------|---------|-------------------
File      | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s 
----------|---------|----------|---------|---------|-------------------
All files |       0 |        0 |       0 |       0 |                   
----------|---------|----------|---------|---------|-------------------
npm ERR! Test failed.  See above for more details.
Error: Process completed with exit code 1.

I have no idea how to further debug this since I'm getting no stack trace 🤔 Ideas on who to ask here?

[JustinBeckwith]

Ok, well that was terrible to figure out. Regardless :) @bcoe could I trouble you for a code review on this one? There are a lot of changes in the ES Modules realm, and I would love a second set of eyes.

[bcoe]

@JustinBeckwith happy to look 👍

[bcoe]

I'm late to the game, but these changes look right to me.

[github-actions]

🎉 This PR is included in version 3.0.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀