Update Pipeline.cs (#778)

src/Microsoft.Tye.Core/Pipeline.cs

@@ -35,11 +35,8 @@ namespace Microsoft.Tye
                 throw new ArgumentNullException(nameof(pipeline));
             }
 
-            foreach (var kvp in callbacks)
+            foreach (var (type, delegates) in callbacks)
             {
-                var type = kvp.Key;
-                var delegates = kvp.Value;
-
                 var method = pipeline.GetType().GetMethod("Register")!.MakeGenericMethod(type);
                 for (var i = 0; i < delegates.Count; i++)
                 {