Update dependency core-js to v3

Author: renovate-bot

package-lock.json

@@ -20,7 +20,7 @@
     "@angular/platform-browser": "8.0.0",
     "@angular/platform-browser-dynamic": "8.0.0",
     "@angular/router": "8.0.0",
-    "core-js": "2.5.4",
+    "core-js": "3.6.4",
     "prettier": "^1.15.2",
     "rxjs": "6.5.2",
     "tslib": "^1.9.0",