Update dependency zone.js to v0.8.20

Author: renovate-bot

basic/package.json

@@ -30,7 +30,7 @@
     "graphql-tag": "1.3.2",
     "rxjs": "5.5.6",
     "ts-helpers": "1.1.2",
-    "zone.js": "0.8.19"
+    "zone.js": "0.8.20"
   },
   "devDependencies": {
     "@angular/cli": "1.6.3",

basic/yarn.lock

@@ -5705,6 +5705,10 @@ zen-observable-ts@^0.4.4:
   version "0.4.4"
   resolved "https://registry.yarnpkg.com/zen-observable-ts/-/zen-observable-ts-0.4.4.tgz#c244c71eaebef79a985ccf9895bc90307a6e9712"
 
-zone.js@0.8.19, zone.js@^0.8.14:
+zone.js@0.8.20:
+  version "0.8.20"
+  resolved "https://registry.yarnpkg.com/zone.js/-/zone.js-0.8.20.tgz#a218c48db09464b19ff6fc8f0d4bb5b1046e185d"
+
+zone.js@^0.8.14:
   version "0.8.19"
   resolved "https://registry.yarnpkg.com/zone.js/-/zone.js-0.8.19.tgz#a4b522cd9e8b7b616a638c297d720d4c7f292f71"