Bump cssnano from 5.0.2 to 5.0.3 in /build/javascript (#1029)

Bumps [cssnano](https://github.com/cssnano/cssnano) from 5.0.2 to 5.0.3.
- [Release notes](https://github.com/cssnano/cssnano/releases)
- [Commits](https://github.com/cssnano/cssnano/compare/cssnano@5.0.2...cssnano@5.0.3)

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build/javascript/package.json

@@ -15,7 +15,7 @@
     "video.js": "7.11.8"
   },
   "devDependencies": {
-    "cssnano": "^5.0.2",
+    "cssnano": "^5.0.3",
     "postcss": "^8.2.15",
     "postcss-cli": "^8.3.1"
   },