Tracking issue for Ember v4.0 compatibility

[raido]

Getting back on track plan for Ember v4.0 (lifted from here -> #217 (comment)):

Tier 1:

• Ember v3.28 upgrade, get builds greenish as beta scenario is allowed to fail -> fix: Update Ember version and use new Embroider testing setup #217
• Cherry pick or ask author to only do assign related changes in this PR - Resolve deprecation re: use Object.assign or spread instead of Ember.… #218
• ember-auto-import 2.x upgrade Use volta for ci + support Ember Beta v4.x and Canary #223
• Release a major version v7.x, because PR fix: Update Ember version and use new Embroider testing setup #217 dropped Node 10 support
• Get ember-page-title updated to v7.x for cli blueprints. -> Bump ember-page-title from v6.2.2 to v7.0.0 ember-cli#9679

Tier 2:

- [ ] ember-auto-import 2.x upgrade
- [ ] Release another major version

[raido]

@knownasilya could you cut v7.x release? 🤞

[knownasilya]

Will try to do that tonight.

[raido]

@knownasilya, actually we don't need two major releases, because ember-auto-import isnt in dependencies list. I'll get #223 reviewed and merged and then we can ship v7.x for all of it.

[raido]

@knownasilya we should be good to go now for v7.x. I also re-deployed https://ember-cli.github.io/ember-page-title/ site and it's running on Ember.js v3.28.4 now :)

[knownasilya]

v7 is published

[raido]

This is completed as of today.