v4.0.0-alpha.6

Thanks to @buschtoens.

Internal

I introduced embroider-css-modules to docs-app, in order to show that ember-container-query is (has long been) compatible with the strictest settings for Embroider.

Remaining tasks for v4.0.0 release

• Drop Node 14 and Ember 3.28 support (after April 30, 2023)