Bump cssnano from 7.0.4 to 7.0.5 in /src/sphinx_antsibull_ext/css (#301)

Bumps [cssnano](https://github.com/cssnano/cssnano) from 7.0.4 to 7.0.5.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@7.0.4...cssnano@7.0.5)

---
updated-dependencies:
- dependency-name: cssnano
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

src/sphinx_antsibull_ext/css/package.json

@@ -1,7 +1,7 @@
 {
   "dependencies": {
     "autoprefixer": "^10.4.20",
-    "cssnano": "^7.0.4",
+    "cssnano": "^7.0.5",
     "postcss": "^8.4.40",
     "postcss-cli": "^11.0.0",
     "sass": "^1.77.8"