Updated CI and dependencies. Dropped support for Node 12 and Ember 3.24 LTS.

[ijlee2]

Description

As a part of emberjs/ember.js#20162 and #387, I will create a few pull requests to update this repo, so that we can ease future maintenance.

I made the following changes in this pull request:

• Commit 1: Dropped support for Node 12. When we are ready to cut a release, we will want to announce a major version.
• Commits 2-4: Updated CI to be readable and make use of v3 actions (caching is simpler). Note that CI failed (error message: Cannot find module '@babel/core'), even though I didn't change any code.
• Commits 5-10: Ran ember-cli-update to update ember-source from 3.28.8 to 4.9.3. Note that CI passed after updating the packages.
• Commits 11-12: Replaced scenario-tester with ember-try (better documentation and support currently). Dropped Ember 3.20 and 3.24 from the test matrix. Added Ember 3.28 and 4.4 to the test matrix.
• Commit 13: Updated the minimum supported versions in README.

References

• https://github.com/ember-cli/ember-cli/tree/v4.9.2/blueprints/addon/files
• https://github.com/embroider-build/addon-blueprint
• https://gist.github.com/ijlee2/1c864ebe96a55f239e80800829ef0bf4

[ijlee2]

Good practice to set timeout-minutes to a low value so that CI can fail early when something goes wrong. (The default value is 360 minutes.)

[ijlee2]

It seemed like, the addon had been made a v2 addon before it was decided (e.g. via https://github.com/embroider-build/addon-blueprint) that workspaces are a good option.

At the moment, I'm thinking that it may be easier to introduce TypeScript before introducing yarn workspace.

[ijlee2]

I'll update eslint to v8 in a separate pull request.

[bertdeblock]

A bit late, but we can also added LTS 4.8 to the test scenario's?

[ijlee2]

@bertdeblock Yep, I think adding 4.8 now is a good idea.

At the moment, I'm investigating why CI failed after merging the PR (seems to be an issue with dependencies). I'll get to both issues soon.

[ijlee2]

The failed CI run seems to be related to a recent change in ember-qunit@v6.1.0.

https://github.com/emberjs/ember-qunit/pull/995/files#r1051368796