Update CI and drop support for Node 12

[mikrostew]

Summary

Fix CI for this repo, which has been failing for the last few months, and run against Node 14.x and 16.x.

Updated Node LTS Versions

This drops support for Node 12.x (which is EOL as of 2022/04/30), and runs the tests against 14.x and 16.x.

I also pinned a more recent version of Yarn.

Notes
I had to update workerpool in the lockfile to pull in the fix for Node16 mentioned in this issue.

Legacy Mocha Tests

These have been failing for a while, with this error:

Error: Unable to require module 'crypto' because it was not in the whitelist.

So I added that to fastbootDependencies, which fixed the issue.

Notes
Running with Node 16 surfaced a new error with starting the server in the tests, so I removed the skipNpm: true option to fix that.

Ember-Try Tests

These have also been failing for a while, with this error:

Build Error (broccoli-persistent-filter:Babel > [Babel: @ember/test-helpers]) in @ember/test-helpers/-internal/build-registry.js

[BABEL]: Cannot find module 'babel-plugin-dynamic-import-node/utils'

I fixed that by preventing ember-try from running with --no-lockfile (which it does by default, and was causing a dependency mismatch when running the tests).

[mikrostew]

I don't have permissions to run CI on this repo, but I was able to successfully run these changes against my fork: mikrostew#3

[ef4]

Thanks, this looks OK so I'm going to merge it so it will actually get CI running again and you can see if it works.