fix(package): update @angular/pwa to version 0.900.6

Closes #80

Author: greenkeeper[bot]

demo/package.json

@@ -38,7 +38,7 @@
     "@angular/platform-browser": "^7.2.0",
     "@angular/platform-browser-dynamic": "^7.2.0",
     "@angular/platform-server": "^7.2.0",
-    "@angular/pwa": "^0.10.7",
+    "@angular/pwa": "^0.900.6",
     "@angular/router": "^7.2.0",
     "@angular/service-worker": "^7.2.0",
     "@ng-bootstrap/ng-bootstrap": "^4.0.1",