SlotHTMLAttributes breaks compatibility with React 16 / 17 (missing peerDependency for React 18)

[RadekJakGit]

Initial checklist

• I read the support docs
• I read the contributing guide
• I agree to follow the code of conduct
• I searched issues and discussions and couldn’t find anything (or linked relevant results below)

Affected package

6.0.0

Steps to reproduce

Version 6.0.0 requires react 18.

Actual behavior

In react-markdown@6.x, the TypeScript definitions use React.SlotHTMLAttributes, which is only available in @types/react@18.0.28+. This causes compilation errors in projects using React 16 or 17, such as:
error TS2724: 'React' has no exported member named 'SlotHTMLAttributes'.

This makes it impossible to use this package with React 16 or 17 without type errors, even though the package technically installs fine due to missing peer dependency checks.

Expected behavior

To improve developer experience and avoid silent breakage, please consider adding:

"peerDependencies": {
  "react": "^18.0.0",
  "react-dom": "^18.0.0"
}


### Runtime

_No response_

### Package manager

_No response_

### Operating system

_No response_

### Build and bundle tools

_No response_

[remcohaszing]

react-markdown@7 was released in 2021. This was 4 years ago. We’re already at 10 now. A lot has improved, also in React and TypeScript. Why are you using such old versions?