Fix tests

Author: javiercn

src/Components/Server/src/CircuitDisconnectMiddleware.cs

@@ -55,7 +55,7 @@ public async Task Invoke(HttpContext context)
         {
             try
             {
-                if (!string.Equals(context.Request.ContentType, "application/x-www-form-urlencoded"))
+                if (!context.Request.HasFormContentType)
                 {
                     return (false, null);
                 }