Update SignalR submodule

Nate McMaster · Nate McMaster · commit ce8cf6558973 · 2018-11-11T20:24:57.000-08:00
diff --git a/modules/SignalR b/modules/SignalR
@@ -1 +1 @@
-Subproject commit a242dc726d714e0a10ed423e1e526e8902b0fc2c
+Subproject commit a9def470e3b8e1480c55d1c311e4b37472140307
