chore(deps-dev): bump postcss (#390)

Bumps the npm_and_yarn group with 1 update in the / directory: [postcss](https://github.com/postcss/postcss).


Updates `postcss` from 8.5.14 to 8.5.18
- [Release notes](https://github.com/postcss/postcss/releases)
- [Changelog](https://github.com/postcss/postcss/blob/main/CHANGELOG.md)
- [Commits](postcss/postcss@8.5.14...8.5.18)

---
updated-dependencies:
- dependency-name: postcss
  dependency-version: 8.5.18
  dependency-type: direct:development
  dependency-group: npm_and_yarn
...

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Author: dependabot[bot]

package.json

@@ -102,7 +102,7 @@
     "husky": "^9.1.7",
     "katex": "^0.16.22",
     "lint-staged": "^16.1.6",
-    "postcss": "^8.5.11",
+    "postcss": "^8.5.18",
     "prettier": "3.6.2",
     "prisma": "^7.4.1",
     "rehype-katex": "^7.0.1",