Bump debug and ember-cli

Bumps [debug](https://github.com/debug-js/debug) to 2.6.9 and updates ancestor dependency [ember-cli](https://github.com/ember-cli/ember-cli). These dependencies need to be updated together.


Updates `debug` from 2.2.0 to 2.6.9
- [Release notes](https://github.com/debug-js/debug/releases)
- [Changelog](https://github.com/debug-js/debug/blob/2.6.9/CHANGELOG.md)
- [Commits](debug-js/debug@2.2.0...2.6.9)

Updates `ember-cli` from 2.16.2 to 2.18.2
- [Release notes](https://github.com/ember-cli/ember-cli/releases)
- [Changelog](https://github.com/ember-cli/ember-cli/blob/master/CHANGELOG.md)
- [Commits](ember-cli/ember-cli@v2.16.2...v2.18.2)

---
updated-dependencies:
- dependency-name: debug
  dependency-type: indirect
- dependency-name: ember-cli
  dependency-type: direct:development
...

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