ext: Update Pybind to Version 2.10.3

Updating Pybind11 is necessary for gem5 to compile correctly with
Python 3.11. As of March 9th 2023, 2.10.3 is the latest version of
Pybind11.

Change-Id: I32c68c507770040d3fac2de442d88a8f46b48896
Issue-on: https://gem5.atlassian.net/browse/GEM5-1295
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/68818
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

ext/pybind11/tests/eigen_tensor_avoid_stl_array.cpp

@@ -0,0 +1,14 @@
+/*
+    tests/eigen_tensor.cpp -- automatic conversion of Eigen Tensor
+
+    All rights reserved. Use of this source code is governed by a
+    BSD-style license that can be found in the LICENSE file.
+*/
+
+#ifndef EIGEN_AVOID_STL_ARRAY
+#    define EIGEN_AVOID_STL_ARRAY
+#endif
+
+#include "test_eigen_tensor.inl"
+
+PYBIND11_MODULE(eigen_tensor_avoid_stl_array, m) { eigen_tensor_test::test_module(m); }