Use SmallVector for shapes and strides (#2454)

* Use SmallVector for shapes and strides

* Convert SmallVector to tuple

python/src/metal.cpp

@@ -7,8 +7,10 @@
 #include <nanobind/stl/unordered_map.h>
 #include <nanobind/stl/variant.h>
 #include <nanobind/stl/vector.h>
+
 #include "mlx/backend/metal/metal.h"
 #include "mlx/memory.h"
+#include "python/src/small_vector.h"
 
 namespace mx = mlx::core;
 namespace nb = nanobind;