fix(package): update @nguniversal/express-engine to version 9.1.0

Closes #99

Author: greenkeeper[bot]

package.json

@@ -53,7 +53,7 @@
     "@angular/platform-server": "^7.2.8",
     "@angular/router": "^7.2.8",
     "@angular/service-worker": "^7.2.8",
-    "@nguniversal/express-engine": "^7.1.1",
+    "@nguniversal/express-engine": "^9.1.0",
     "@nguniversal/module-map-ngfactory-loader": "^7.1.1",
     "@ngx-translate/core": "^11.0.1",
     "angulartics2": "^7.4.1",