Bump postcss from 8.5.14 to 8.5.15 in /web

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.14 to 8.5.15.
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.14...8.5.15)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.15
  dependency-type: direct:development
  update-type: version-update:semver-patch
...

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

Author: dependabot[bot]

web/package-lock.json

@@ -51,7 +51,7 @@
     "eslint-plugin-react": "^7.37.5",
     "eslint-plugin-react-hooks": "^7.1.1",
     "globals": "^17.6.0",
-    "postcss": "^8.5.14",
+    "postcss": "^8.5.15",
     "react-router-dom": "^7.15.1",
     "tailwindcss": "^4.3.0",
     "typescript": "^6.0.3",