chore(package): update @angular-devkit/core to version 9.1.7

Closes #48

Author: greenkeeper[bot]

demo/package.json

@@ -49,7 +49,7 @@
   },
   "devDependencies": {
     "@angular-devkit/build-angular": "^0.10.7",
-    "@angular-devkit/core": "^7.3.5",
+    "@angular-devkit/core": "^9.1.7",
     "@angular-devkit/schematics": "^7.3.5",
     "@angular/cli": "^7.3.5",
     "@angular/compiler-cli": "^7.2.8",