Bump ember-source from 4.11.0 to 5.12.0 in /smoke-test-app

Bumps [ember-source](https://github.com/emberjs/ember.js) from 4.11.0 to 5.12.0.
- [Release notes](https://github.com/emberjs/ember.js/releases)
- [Changelog](https://github.com/emberjs/ember.js/blob/main/CHANGELOG.md)
- [Commits](emberjs/ember.js@v4.11.0...v5.12.0)

---
updated-dependencies:
- dependency-name: ember-source
  dependency-type: direct:development
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>