chore: Upgrade to TypeScript 5.4

[slorber]

Motivation

Upgrade to latest TS stable version

Note: I'm not yet using mode-resolution (ttps://github.com/microsoft/TypeScript/issues/49721) (TS 5.3) because:

• I need to check if it impacts user min TS version, it might be a breaking change
• Our version of Prettier does not support import attributes yet, we need to upgrade it first

import type {Transformer} from 'unified' with {"resolution-mode": "import"};

Test Plan

CI + min/max range tests (see #10063)

Test links

https://deploy-preview-10076--docusaurus-2.netlify.app/

[netlify]

✅ [V2]

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🔨 Latest commit	31d5eee
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[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 65	🟢 98	🟢 96	🟢 100	🟠 88	Report
/docs/installation	🟠 59	🟢 96	🟢 100	🟢 100	🟠 88	Report
/docs/category/getting-started	🟠 74	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog	🟠 66	🟢 100	🟢 100	🟢 90	🟠 88	Report
/blog/preparing-your-site-for-docusaurus-v3	🟠 63	🟢 96	🟢 100	🟢 100	🟠 88	Report
/blog/tags/release	🟠 68	🟢 100	🟢 100	🟠 80	🟠 88	Report
/blog/tags	🟠 75	🟢 100	🟢 100	🟢 90	🟠 88	Report

[github-actions]

Size Change: 0 B

Total Size: 1.59 MB

ℹ️ View Unchanged

Filename	Size
website/.docusaurus/codeTranslations.json	2 B
website/.docusaurus/docusaurus.config.mjs	26.7 kB
website/.docusaurus/globalData.json	91.2 kB
website/.docusaurus/i18n.json	930 B
website/.docusaurus/registry.js	247 kB
website/.docusaurus/routes.js	156 kB
website/.docusaurus/routesChunkNames.json	109 kB
website/.docusaurus/site-metadata.json	2.17 kB
website/build/assets/css/styles.********.css	113 kB
website/build/assets/js/main.********.js	810 kB
website/build/index.html	38 kB

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[csantos-nydig]

Hey @slorber I landed here because of the reference I found in code:

docusaurus/packages/docusaurus-mdx-loader/src/processor.ts

Lines 25 to 31 in b6644d8

	// @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
	import type {ProcessorOptions} from '@mdx-js/mdx';
	// TODO as of April 2023, no way to import/re-export this ESM type easily :/
	// This might change soon, likely after TS 5.2
	// See https://github.com/microsoft/TypeScript/issues/49721#issuecomment-1517839391
	type Pluggable = any; // TODO fix this asap

I wonder if that type can be cleaned up now?

---

Context:
I have a bunch of custom rehypePlugins plugins, that I need to TS-type but not sure how to type them now 😞

[slorber]

@csantos-nydig you can do the cleanup in your own codebase

But we can't do it on Docusaurus because it would emit d.ts files with newer TS features which require all users to upgrade TS (breaking change). We'll do the cleanup for the next major version.