Bump css-what from 2.1.0 to 2.1.3 in /fixtures/fiber-debugger (#25430)

Bumps [css-what](https://github.com/fb55/css-what) from 2.1.0 to 2.1.3.
- [Release notes](https://github.com/fb55/css-what/releases)
- [Commits](fb55/css-what@v2.1.0...v2.1.3)

---
updated-dependencies:
- dependency-name: css-what
  dependency-type: indirect
...

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

fixtures/fiber-debugger/yarn.lock

@@ -1411,8 +1411,8 @@ css-selector-tokenizer@^0.7.0:
     regexpu-core "^1.0.0"
 
 css-what@2.1:
-  version "2.1.0"
-  resolved "https://registry.yarnpkg.com/css-what/-/css-what-2.1.0.tgz#9467d032c38cfaefb9f2d79501253062f87fa1bd"
+  version "2.1.3"
+  resolved "https://registry.yarnpkg.com/css-what/-/css-what-2.1.3.tgz#a6d7604573365fe74686c3f311c56513d88285f2"
 
 cssesc@^0.1.0:
   version "0.1.0"