feat: drop Node 8 & 10 support

[MichaelDeBoey]

• In order to properly support ESLint 7.x and upwards, we need to start using @eslint/eslintrc (at least v0.4.3): @eslint/eslintrc/lib/config-array-factory instead of eslint/lib/cli-engine/config-array-factory.
  This however needs Node@^10.12.0 || 12.0.0.
  https://github.com/eslint/eslintrc/blob/9bf2ba12e6c0bfe7296774531fd79dea23d4c805/package.json#L60-L62

• If we want to update our @typescript-eslint/* dependency to v3, we also need Node@^10.12.0 || 12.0.0
  https://github.com/typescript-eslint/typescript-eslint/blob/43b1201a73687e29f19a16b0b26f68569f3c7a2e/package.json#L65-L67

• If we want to update our eslint-plugin-eslint-plugin dependency to v3, we also need Node@^10.12.0 || 12.0.0
  https://github.com/not-an-aardvark/eslint-plugin-eslint-plugin/blob/cc58d764f3c3c342dcb7551c3f4e00abdd32fe19/package.json#L63-L65

• If we want to update our prettier dependency to v2, we need Node@>=10.13.0
  https://github.com/prettier/prettier/blob/2afc3b9ae674ede93489b55ab3f90ba2bcdd27c5/package.json#L13-L15

• Node 8 is EOL, so it's a good practice to not support it anymore.

• Node 10 is EOL, so it's a good practice to not support it anymore.

• ESLint 7.x requires Node@^10.12.0 || >=12.0.0 and imo it's a good practice to keep the Node version equal to that of the latest supported ESLint version
  https://github.com/eslint/eslint/blob/83cc8a6823d7729297b6814a644cca770cb99dbb/package.json#L143-L145

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BREAKING CHANGE: Requires Node@^12.22.0 || ^14.17.0 || >=16.0.0

This branch is dependent on #33

CC/ @voxpelli

[voxpelli]

Node 10, 13 and 15 are also not supported anymore.

I would therefore suggest adopting an ESM compatible versioning: ^12.20.0 || ^14.13.1 || >=16.0.0

[MichaelDeBoey]

@voxpelli I wanted to do it gradually (as that would make the upgrade of this package in other packages easier too), but sure I can go straight to ESLint 8.x's engines

[MichaelDeBoey]

For people watching this PR: we've started already 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 PR is released in @eslint-community/eslint-plugin-mysticatea v14.0.0
https://github.com/eslint-community/eslint-plugin-mysticatea/releases/tag/v14.0.0