feat!: drop Node 12, 14, 16 & 18 support

[MichaelDeBoey]

BREAKING CHANGE: Requires Node@^20.19.0 || ^22.13.0 || >=24

[G-Rath]

I don't have any plans for a new major right now

[MichaelDeBoey]

@G-Rath This PR is against the alpha branch, so we're not going to be releasing a new major with merging this PR

This plugin hasn't been kept up-to-date for a very long time, so I would like to bring it in line with what we've done with all plugins we maintain with the @eslint-community org

[G-Rath]

@MichaelDeBoey this plugin is up to date, I did a lot of work in making that the case when I took over maintaining this plugin.

I'm not against doing new majors, I just don't see a pressing need to do one right now given the plugin is very mature and the extra effort + code to support the older versions is very minor.

This is also why I've not done a new major for eslint-plugin-jest - at this point I'm expecting I'll probably look at doing a new major around the time ESLint v11 comes out.

[MichaelDeBoey]

@G-Rath As said before: these breaking PRs are merged in alpha, meaning we won't cut a major before merging it to main, so these PRs can already be merged without any problem if you ask me 🤷‍♂️

With ESLint v10 released recently, the ESLint TSC and @eslint-community core team (which I'm a member of) is trying to get as much plugins to have an updated codebase
Mainly trying to get everyone to update their configs to at least flat configs, which is (partly) done by removing support for older ESLint versions (see #495)

I personally would just cut a major release right now with all these breaking changes.
People who aren't ready to upgrade can keep using v5 and people who are already on ESLint@>=8.57.0 and Node@>=20.19.0 can just upgrade to v6 without any problems