[chore] bump eslint from version 7 to 8

[stvnwn]

When a user creates a SvelteKit app with eslint support using create-svelte, it ships the last eslint release under major version 7. With this pull request, create-svelte will now ship the latest eslint release (for now).

I'm worried that eslint-plugin-svelte3 doesn't support eslint@^8.0.0, from this discussion.

eslint-plugin-svelte3's peerDependencies lists eslint@>=6.0.0 since June 22, 2019, around when eslint@6.0.1 was released.

Related: #3261

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🦋 Changeset detected

Latest commit: 2bd4f9f

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
create-svelte	Patch

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[dummdidumm]

I think we should first release a new major for eslint-plugin-svelte3 which officially supports ESLint 8, drops NodeJS 10 support etc and then continue here. @Conduitry would you be ok with that?

[Conduitry]

That sounds fine to me. Is there any benefit to dropping Node 12 while we're at it, because it's EOL at the end of the month anyway?

[benmccann]

The eslint plugin tests currently use an internal eslint class. eslint 8 adds an exports map that stops us from using it. I've sent eslint/eslint#15776 to unblock it.

If that doesn't work we can see if we can hack around that by doing something like require.resolve('eslint/package.json') and then constructing the path of the module we want to require since we can probably require an absolute or relative path, regardless of export maps.