feat: dropping support for node 12

[erunion]

⚠️ Do not merge this until the new Github Action workflow has been tagged to the current v6 release series.

🧰 Changes

Node 12 hits EOL in April and with our new action in #437 it'd be nice to start with a clean start, breaking change for folks, so we might as well drop support for Node 12 now and publish a breaking change rather than having to publish another breaking change in a few months.

This also allows us to finally start using optional chaining in this codebase as that was introduced in Node 14.

🧬 QA & Testing

• All tests still passing?

[kanadgupta]

Found a few other places we could swap out:

rdme/bin/rdme

Line 20 in a5e8fdb

if (err && 'message' in err) {

rdme/src/lib/prompts.js

Line 151 in a5e8fdb

return opts.main || (isUpdate && isUpdate.is_stable);

[kanadgupta]

Much cleaner 🎉