fix(package): update @angular/cdk to version 8.1.1

Closes #34

Author: greenkeeper[bot]

demo/package.json

@@ -27,7 +27,7 @@
   "private": true,
   "dependencies": {
     "@angular/animations": "7.2.5",
-    "@angular/cdk": "^7.3.6",
+    "@angular/cdk": "^8.1.1",
     "@angular/common": "7.2.5",
     "@angular/compiler": "7.2.5",
     "@angular/core": "7.2.5",