Handle Error Body in Responses from Broker (#3454)

src/Sdk/RSWebApi/Contracts/BrokerErrorKind.cs

@@ -0,0 +1,10 @@
+using System.Runtime.Serialization;
+
+namespace GitHub.Actions.RunService.WebApi
+{
+    [DataContract]
+    public class BrokerErrorKind
+    {
+        public const string RunnerVersionTooOld = "RunnerVersionTooOld";
+    }
+}