Update dependency rxjs to v6.6.0

Author: renovate-bot

package.json

@@ -24,7 +24,7 @@
     "@angular/platform-browser-dynamic": "9.1.9",
     "@angular/router": "9.1.9",
     "@angular/service-worker": "9.1.9",
-    "rxjs": "6.5.5",
+    "rxjs": "6.6.0",
     "tslib": "1.13.0",
     "zone.js": "0.10.3"
   },