fix(package): update @angular-devkit/core to version 9.1.4

Closes #164

Author: greenkeeper[bot]

package.json

@@ -101,7 +101,7 @@
   "dependencies": {
     "@angular-devkit/architect": "0.13.9",
     "@angular-devkit/build-angular": "0.13.9",
-    "@angular-devkit/core": "7.3.9",
+    "@angular-devkit/core": "9.1.4",
     "@angular-devkit/schematics": "7.3.9",
     "@nestjs/common": "6.1.1",
     "@nestjs/core": "6.1.1",