chore(deps-dev): bump lightningcss from 1.27.0 to 1.28.1 in /backend

Bumps [lightningcss](https://github.com/parcel-bundler/lightningcss) from 1.27.0 to 1.28.1.
- [Release notes](https://github.com/parcel-bundler/lightningcss/releases)
- [Commits](https://github.com/parcel-bundler/lightningcss/commits)

---
updated-dependencies:
- dependency-name: lightningcss
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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

backend/package.json

@@ -59,7 +59,7 @@
         "date-fns": "^4.1.0",
         "easytimer.js": "^4.6.0",
         "highlight.js": "^11.10.0",
-        "lightningcss": "^1.27.0",
+        "lightningcss": "^1.28.1",
         "marked": "^14.1.3",
         "marked-emoji": "^1.4.2",
         "marked-highlight": "^2.2.0",