update package.json and yarn.lock

Author: Marc Neuhaus

package.json

@@ -69,8 +69,9 @@
     "preact": "^8.2.1",
     "preact-compat": "^3.17.0",
     "sass-loader": "^6.0.3",
-    "stylus-loader": "^3.0.1",
     "sinon": "^2.3.4",
+    "stylus": "^0.54.5",
+    "stylus-loader": "^3.0.1",
     "ts-loader": "^2.1.0",
     "typescript": "^2.3.4",
     "vue": "^2.3.4",