Add ExecCredentialResponseContext for JSON serialization support

Author: k7o

src/KubernetesClient.Aot/KubeConfigModels/ExecCredentialResponseContext.cs

@@ -0,0 +1,7 @@
+namespace k8s.KubeConfigModels
+{
+    [JsonSerializable(typeof(ExecCredentialResponse))]
+    internal partial class ExecCredentialResponseContext : JsonSerializerContext
+    {
+    }
+}

src/KubernetesClient.Aot/KubernetesClientConfiguration.ConfigFile.cs

@@ -523,7 +523,10 @@ public static ExecCredentialResponse ExecuteExternalCommand(ExternalExecution co
                     throw new KubeConfigException("external exec failed due to timeout");
                 }
 
-                var responseObject = KubernetesJson.Deserialize<ExecCredentialResponse>(process.StandardOutput.ReadToEnd());
+                var responseObject = JsonSerializer.Deserialize(
+                    process.StandardOutput.ReadToEnd(),
+                    ExecCredentialResponseContext.Default.ExecCredentialResponse);
+
                 if (responseObject == null || responseObject.ApiVersion != config.ApiVersion)
                 {
                     throw new KubeConfigException(