FIX: Tasks on MacOS agents not completing but marked as succeeded.

src/Agent.Sdk/ProcessInvoker.cs

@@ -404,6 +404,10 @@ protected virtual void Dispose(bool disposing)
             {
                 if (_proc != null)
                 {
+                    //Dispose the standard output/error stream. Refer: https://github.com/dotnet/runtime/issues/58872
+                    _proc.StandardOutput?.Dispose();
+                    _proc.StandardError?.Dispose();
+
                     _proc.Dispose();
                     _proc = null;
                 }