chore(deps): bump undici from 6.19.8 to 6.21.1 in /documentation (#460)

Bumps [undici](https://github.com/nodejs/undici) from 6.19.8 to 6.21.1.
- [Release notes](https://github.com/nodejs/undici/releases)
- [Commits](nodejs/undici@v6.19.8...v6.21.1)

---
updated-dependencies:
- dependency-name: undici
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

documentation/yarn.lock

@@ -9596,9 +9596,9 @@ undici-types@~6.19.2:
   integrity sha512-ve2KP6f/JnbPBFyobGHuerC9g1FYGn/F8n1LWTwNxCEzd6IfqTwUQcNXgEtmmQ6DlRrC1hrSrBnCZPokRrDHjw==
 
 undici@^6.19.5:
-  version "6.19.8"
-  resolved "https://registry.yarnpkg.com/undici/-/undici-6.19.8.tgz#002d7c8a28f8cc3a44ff33c3d4be4d85e15d40e1"
-  integrity sha512-U8uCCl2x9TK3WANvmBavymRzxbfFYG+tAu+fgx3zxQy3qdagQqBLwJVrdyO1TBfUXvfKveMKJZhpvUYoOjM+4g==
+  version "6.21.1"
+  resolved "https://registry.yarnpkg.com/undici/-/undici-6.21.1.tgz#336025a14162e6837e44ad7b819b35b6c6af0e05"
+  integrity sha512-q/1rj5D0/zayJB2FraXdaWxbhWiNKDvu8naDT2dl1yTlvJp4BLtOcp2a5BvgGNQpYYJzau7tf1WgKv3b+7mqpQ==
 
 unicode-canonical-property-names-ecmascript@^2.0.0:
   version "2.0.1"