feat: add react v19 to peer deps

[Yonom]

Thanks a lot for this package

I get the following warning from pnpm after upgrading to NextJS v15 (released today), which installs react 19 RC

React 19 is technically still in RC stage, but since a stable version of a major Metaframework is installing it, it's a sign that it's ready for production use and will now be used by many projects.

│ └─┬ next-themes 0.3.0
│   ├── ✕ unmet peer react@"^16.8 || ^17 || ^18": found 19.0.0-rc-65a56d0e-20241020
│   └── ✕ unmet peer react-dom@"^16.8 || ^17 || ^18": found 19.0.0-rc-65a56d0e-20241020

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
next-themes-basic	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Oct 22, 2024 0:52am
next-themes-tailwind	❌ Failed (Inspect)			Oct 22, 2024 0:52am
next-themes-with-app-dir	❌ Failed (Inspect)			Oct 22, 2024 0:52am

[bannednull]

It worked for me like this