chore(deps-dev): bump @primer/css from 21.3.6 to 21.5.1 (#5530)

Bumps [@primer/css](https://github.com/primer/css) from 21.3.6 to 21.5.1.
- [Release notes](https://github.com/primer/css/releases)
- [Changelog](https://github.com/primer/css/blob/main/CHANGELOG.md)
- [Commits](primer/css@v21.3.6...v21.5.1)

---
updated-dependencies:
- dependency-name: "@primer/css"
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

packages/react/package.json

@@ -116,7 +116,7 @@
     "@babel/preset-react": "7.24.7",
     "@babel/preset-typescript": "7.24.7",
     "@figma/code-connect": "1.2.4",
-    "@primer/css": "^21.3.6",
+    "@primer/css": "^21.5.1",
     "@rollup/plugin-babel": "6.0.4",
     "@rollup/plugin-commonjs": "25.0.4",
     "@rollup/plugin-node-resolve": "15.1.0",