fix(package): update @adobe/helix-simulator to version 2.12.4

Author: greenkeeper[bot]

package-lock.json

@@ -36,7 +36,7 @@
     "@adobe/fastly-native-promises": "^1.3.2",
     "@adobe/helix-pipeline": "^1.5.0",
     "@adobe/helix-shared": "1.1.1",
-    "@adobe/helix-simulator": "2.12.3",
+    "@adobe/helix-simulator": "2.12.4",
     "@adobe/parcel-plugin-htl": "2.1.4",
     "@babel/core": "^7.4.3",
     "@parcel/logger": "1.11.0",