[Docs Site] Bump tailwindcss from 3.4.17 to 4.1.15

Bumps [tailwindcss](https://github.com/tailwindlabs/tailwindcss/tree/HEAD/packages/tailwindcss) from 3.4.17 to 4.1.15.
- [Release notes](https://github.com/tailwindlabs/tailwindcss/releases)
- [Changelog](https://github.com/tailwindlabs/tailwindcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/tailwindlabs/tailwindcss/commits/v4.1.15/packages/tailwindcss)

---
updated-dependencies:
- dependency-name: tailwindcss
  dependency-version: 4.1.15
  dependency-type: direct:development
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]