fix(tests): use correct ScalarType namespace

Change from executorch::runtime::ScalarType to executorch::aten::ScalarType
to fix compilation errors in TensorHelpersTest.

Author: benITo47

packages/react-native-executorch/common/rnexecutorch/tests/unit/TensorHelpersTest.cpp

@@ -6,9 +6,9 @@
 #include <vector>
 
 using namespace rnexecutorch::utils::tensor;
+using executorch::aten::ScalarType;
 using executorch::extension::make_tensor_ptr;
 using executorch::runtime::EValue;
-using executorch::runtime::ScalarType;
 
 // ============================================================================
 // toSpan<T>(Tensor) — Convert tensor to typed span