fix(package): update @angular/pwa to version 0.12.3

Closes #48

Author: greenkeeper[bot]

demo/package.json

@@ -37,7 +37,7 @@
     "@angular/platform-browser": "^7.0.2",
     "@angular/platform-browser-dynamic": "^7.0.2",
     "@angular/platform-server": "^7.0.2",
-    "@angular/pwa": "^0.10.4",
+    "@angular/pwa": "^0.12.3",
     "@angular/router": "^7.0.2",
     "@angular/service-worker": "^7.0.2",
     "@ng-bootstrap/ng-bootstrap": "^4.0.0",