Bump stylus from 0.54.8 to 0.56.0 in /template

Bumps [stylus](https://github.com/stylus/stylus) from 0.54.8 to 0.56.0.
- [Release notes](https://github.com/stylus/stylus/releases)
- [Changelog](https://github.com/stylus/stylus/blob/dev/Changelog.md)
- [Commits](stylus/stylus@0.54.8...0.56.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

template/package.json

@@ -28,7 +28,7 @@
     "nuxt": "^2.15.8",
     "node-sass": "^6.0.1",
     "sass-loader": "10.2.0",
-    "stylus": "0.54.8",
+    "stylus": "0.56.0",
     "stylus-loader": "6.2.0",
     "electron-devtools-installer": "^3.2.0",
     "vuetify": "^2.5.10",