Update dependency ember-source to v3.28.7

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
ember-source (source)	3.28.6 -> 3.28.7

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Release Notes

emberjs/ember.js

### [`v3.28.7`](https://togithub.com/emberjs/ember.js/blob/master/CHANGELOG.md#v3287-December-1-2021) [Compare Source](https://togithub.com/emberjs/ember.js/compare/v3.28.6...v3.28.7) - [#​19854](https://togithub.com/emberjs/ember.js/pull/19854) \[BUGFIX] Fix implicit injections deprecation for routes to cover previously missed cases - [#​19857](https://togithub.com/emberjs/ember.js/pull/19857) \[BUGFIX] Improve assert message in default store for when routes have dynamic segments but no model hook

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