Bump testdouble from 3.9.0 to 3.9.1 (#310)
Bump testdouble from 3.9.0 to 3.9.1 (#310)

Bumps [testdouble](https://github.com/testdouble/testdouble.js) from 3.9.0 to 3.9.1.
- [Release notes](https://github.com/testdouble/testdouble.js/releases)
- [Changelog](https://github.com/testdouble/testdouble.js/blob/master/CHANGELOG.md)
- [Commits](https://github.com/testdouble/testdouble.js/compare/v3.9.0...v3.9.1)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
jonathanKingston/ember-cli-eslint,ember-cli/ember-cli-eslint,ember-cli/ember-cli-eslint,jonathanKingston/ember-cli-eslint