Bump undici and @astrojs/cloudflare

Bumps [undici](https://github.com/nodejs/undici) to 5.26.4 and updates ancestor dependency [@astrojs/cloudflare](https://github.com/withastro/adapters/tree/HEAD/packages/cloudflare). These dependencies need to be updated together.


Updates `undici` from 5.23.0 to 5.26.4
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v5.23.0...v5.26.4)

Updates `@astrojs/cloudflare` from 7.5.1 to 7.6.1
- [Release notes](https://github.com/withastro/adapters/releases)
- [Changelog](https://github.com/withastro/adapters/blob/main/packages/cloudflare/CHANGELOG.md)
- [Commits](https://github.com/withastro/adapters/commits/@astrojs/[email protected]/packages/cloudflare)

---
updated-dependencies:
- dependency-name: undici
  dependency-type: indirect
- dependency-name: "@astrojs/cloudflare"
  dependency-type: direct:production
...

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