Support ESLint 8.x

[MichaelDeBoey]

ESLint v8.0.0 is released 🎉

It would be awesome to have official ESLint 8 support. 👊
I'm happy to help where I can of course 🙂

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Follow-up of #28

[MichaelDeBoey]

For people watching this issue: we've already started with our own fork in order to not hold the wider community back anymore: https://github.com/eslint-community/eslint-plugin-mysticatea

@mysticatea We would still love to move the original repo to the new https://github.com/eslint-community though.

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This is released in @eslint-community/eslint-plugin-mysticatea v15.2.0
https://github.com/eslint-community/eslint-plugin-mysticatea/releases/tag/v15.2.0