Upgrade AngleSharp to 0.9.6

Author: kevinchalet

src/AspNet.Security.OpenId/project.json

@@ -30,7 +30,7 @@
   },
 
   "dependencies": {
-    "AngleSharp": "0.9.4",
+    "AngleSharp": "0.9.6",
     "JetBrains.Annotations": { "type": "build", "version": "10.1.4" },
     "Microsoft.AspNetCore.Authentication": "1.0.0-rc2-*",
     "Newtonsoft.Json": "8.0.3"