Update dependency @ember/test-helpers to v2.9.3

[renovate[bot]]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
@ember/test-helpers	2.9.1 -> 2.9.3

---

Release Notes

emberjs/ember-test-helpers

### [`v2.9.3`](https://togithub.com/emberjs/ember-test-helpers/releases/tag/v2.9.3): Release 2.9.3 [Compare Source](https://togithub.com/emberjs/ember-test-helpers/compare/v2.9.2...v2.9.3) ##### :bug: Bug Fix - [#​1305](https://togithub.com/emberjs/ember-test-helpers/pull/1305) \[backport] Avoid unnecessary dependencies on `@glimmer` types ([@​dfreeman](https://togithub.com/dfreeman)) ##### Committers: 1 - Dan Freeman ([@​dfreeman](https://togithub.com/dfreeman)) ### [`v2.9.2`](https://togithub.com/emberjs/ember-test-helpers/releases/tag/v2.9.2): Release 2.9.2 [Compare Source](https://togithub.com/emberjs/ember-test-helpers/compare/v2.9.1...v2.9.2) ##### :bug: Bug Fix - [#​1302](https://togithub.com/emberjs/ember-test-helpers/pull/1302) \[backport] Remove the index signature from `TestContext` ([@​chriskrycho](https://togithub.com/chriskrycho)) - Backporting [#​1301](https://togithub.com/emberjs/ember-test-helpers/pull/1301) Remove the index signature from `TestContext` ([@​dfreeman](https://togithub.com/dfreeman)) - [#​1303](https://togithub.com/emberjs/ember-test-helpers/pull/1303) `TestContext.resumeTest()` returns `void`, not `Promise` ([@​chriskrycho](https://togithub.com/chriskrycho)) ##### Committers: 1 - Chris Krycho ([@​chriskrycho](https://togithub.com/chriskrycho)) - Dan Freeman ([@​dfreeman](https://togithub.com/dfreeman))

---

Configuration

📅 Schedule: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined).

🚦 Automerge: Enabled.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about this update again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR has been generated by Mend Renovate. View repository job log here.