Bump rehype-katex from 5.0.0 to 7.0.0 in /website

Bumps [rehype-katex](https://github.com/remarkjs/remark-math) from 5.0.0 to 7.0.0.
- [Release notes](https://github.com/remarkjs/remark-math/releases)
- [Commits](https://github.com/remarkjs/remark-math/compare/[email protected]@7.0.0)

---
updated-dependencies:
- dependency-name: rehype-katex
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>