Bump postcss from 8.3.2 to 8.3.3 in /build/javascript (#1102)

Bumps [postcss](https://github.com/postcss/postcss) from 8.3.2 to 8.3.3.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](https://github.com/postcss/postcss/compare/8.3.2...8.3.3)

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

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build/javascript/package.json

@@ -15,7 +15,7 @@
   },
   "devDependencies": {
     "cssnano": "^5.0.6",
-    "postcss": "^8.3.2",
+    "postcss": "^8.3.3",
     "postcss-cli": "^8.3.1"
   },
   "snowpack": {