fix TensorSharp.concatenate

src/TensorFlowNET.Core/Tensors/TensorShape.cs

@@ -67,7 +67,16 @@ namespace Tensorflow
             if (NDim < 0 || other.NDim < 0)
                 return new TensorShape();
             else
-                return new TensorShape(NDim + other.NDim);
+            {
+                var concatenate_dims = new int[NDim + other.NDim];
+                for (int i = 0; i < NDim; i++)
+                    concatenate_dims[i] = dims[i];
+
+                for (int i = 0; i < other.NDim; i++)
+                    concatenate_dims[NDim + i] = other.dims[i];
+
+                return new TensorShape(concatenate_dims);
+            }
         }
 
         public static implicit operator TensorShape(int[] dims) => new TensorShape(dims);