Bump http-cache-semantics and ember-cli (#1897)

Removes [http-cache-semantics](https://github.com/kornelski/http-cache-semantics). It's no longer used after updating ancestor dependency [ember-cli](https://github.com/ember-cli/ember-cli). These dependencies need to be updated together.


Removes `http-cache-semantics`

Updates `ember-cli` from 3.16.2 to 3.28.6
- [Release notes](https://github.com/ember-cli/ember-cli/releases)
- [Changelog](https://github.com/ember-cli/ember-cli/blob/v3.28.6/CHANGELOG.md)
- [Commits](ember-cli/ember-cli@v3.16.2...v3.28.6)

---
updated-dependencies:
- dependency-name: http-cache-semantics
  dependency-type: indirect
- dependency-name: ember-cli
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]