Bump cssnano from 5.0.5 to 5.0.6 in /build/javascript (#1095)

Bumps [cssnano](https://github.com/cssnano/cssnano) from 5.0.5 to 5.0.6.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@5.0.5...cssnano@5.0.6)

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

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

build/javascript/package.json

@@ -14,7 +14,7 @@
     "video.js": "7.12.3"
   },
   "devDependencies": {
-    "cssnano": "^5.0.5",
+    "cssnano": "^5.0.6",
     "postcss": "^8.3.2",
     "postcss-cli": "^8.3.1"
   },