build(deps-dev): bump postcss from 8.5.15 to 8.5.18 (#1269)

Bumps [postcss](https://github.com/postcss/postcss) from 8.5.15 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@8.5.15...8.5.18)

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

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

package-lock.json

@@ -68,7 +68,7 @@
         "lodash-es": "^4.18.1",
         "luminous-lightbox": "^2.4.0",
         "mitt": "^3.0.1",
-        "postcss": "^8.5.6",
+        "postcss": "^8.5.18",
         "postcss-100vh-fix": "^2.0.0",
         "prettier": "^3.0.0",
         "prettier-plugin-tailwindcss": "^0.6.14",