make sure rawScheme is in lower case

EVCB_OCPP.WSServer/Service/WsService/WebsocketService.cs

@@ -139,8 +139,9 @@ public class WebsocketService<T> where T : WsSession
 
         if (string.IsNullOrEmpty(rawScheme))
         {
-            rawScheme = context.Request.Scheme.ToLower();
+            rawScheme = context.Request.Scheme;
         }
+        rawScheme = rawScheme.ToLower();
         if (rawScheme == "http" ||
             rawScheme == "ws")
         {