Bump postcss from 8.5.8 to 8.5.12 in /web

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.8 to 8.5.12.
- [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/8.5.8...8.5.12)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.12
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

web/package.json

@@ -131,7 +131,7 @@
     "monaco-editor": "^0.52.2",
     "msw": "^2.3.5",
     "patch-package": "^8.0.1",
-    "postcss": "^8.5.8",
+    "postcss": "^8.5.12",
     "prettier": "^3.3.3",
     "prettier-plugin-tailwindcss": "^0.6.5",
     "tailwindcss": "^3.4.9",