Update eslint-config-airbnb to version 6.1.0 🚀

[greenkeeperio-bot]

Hello :wave:

:rocket::rocket::rocket:

eslint-config-airbnb just published its new version 6.1.0, which is not covered by your current version range.

If this pull request passes your tests you can publish your software with the latest version of eslint-config-airbnb – otherwise use this branch to work on adaptions and fixes.

Happy fixing and merging :palm_tree:

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