Update eslint-config-airbnb-base to the latest version 🚀

[greenkeeper[bot]]

Version 12.0.0 of eslint-config-airbnb-base just got published.

Dependency	eslint-config-airbnb-base
Current Version	11.3.2
Type	devDependency

The version 12.0.0 is not covered by your current version range.

Without accepting this pull request your project will work just like it did before. There might be a bunch of new features, fixes and perf improvements that the maintainers worked on for you though.

I recommend you look into these changes and try to get onto the latest version of eslint-config-airbnb-base. Given that you have a decent test suite, a passing build is a strong indicator that you can take advantage of these changes by merging the proposed change into your project. Otherwise this branch is a great starting point for you to work on the update.

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Not sure how things should work exactly?

There is a collection of [frequently asked questions](https://greenkeeper.io/faq.html) and of course you may always [ask my humans](https://github.com/greenkeeperio/greenkeeper/issues/new).

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Your Greenkeeper Bot :palm_tree:

[coveralls]

Coverage remained the same at 100.0% when pulling 8aec6d1afe99ffb7fc194f7ff2daea4eedbacff3 on greenkeeper/eslint-config-airbnb-base-12.0.0 into 17c8a8c46e3ff6c321db30a974382829d53539fa on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 8aec6d1afe99ffb7fc194f7ff2daea4eedbacff3 on greenkeeper/eslint-config-airbnb-base-12.0.0 into 17c8a8c46e3ff6c321db30a974382829d53539fa on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 8aec6d1afe99ffb7fc194f7ff2daea4eedbacff3 on greenkeeper/eslint-config-airbnb-base-12.0.0 into 17c8a8c46e3ff6c321db30a974382829d53539fa on master.