Updated Renovate configuration (#1137)
Updated Renovate configuration (#1137)

no issue
- ignore `ember-exam` until it's compatible with latest stable of `ember-mocha`
  - see https://github.com/ember-cli/ember-exam/issues/238
- moved `ember-exam`, `ember-mocha`, and `testem` into their own group so changes to test env don't cause addon upgrade PRs to fail
TryGhost/Ghost-Admin,kevinansfield/Ghost-Admin,TryGhost/Ghost-Admin,kevinansfield/Ghost-Admin