build fails with icu 75

[andyrtr]

Building with recent icu 75.1/harfbuzz-icu give this build failure:

   Compiling tracing v0.1.40
The following warnings were emitted during compilation:

warning: tectonic_xetex_layout@0.2.4: In file included from /usr/include/unicode/ubidi.h:26,
warning: tectonic_xetex_layout@0.2.4:                  from layout/xetex-XeTeXLayoutInterface.cpp:36:
warning: tectonic_xetex_layout@0.2.4: /usr/include/unicode/localpointer.h:561:26: error: ‘auto’ parameter not permitted in this context
warning: tectonic_xetex_layout@0.2.4:   561 | template <typename Type, auto closeFunction>
warning: tectonic_xetex_layout@0.2.4:       |                          ^~~~
warning: tectonic_xetex_layout@0.2.4: /usr/include/unicode/localpointer.h:573:76: error: template argument 2 is invalid
warning: tectonic_xetex_layout@0.2.4:   573 |     explicit LocalOpenPointer(std::unique_ptr<Type, decltype(closeFunction)> &&p)
warning: tectonic_xetex_layout@0.2.4:       |                                                                            ^
warning: tectonic_xetex_layout@0.2.4: /usr/include/unicode/localpointer.h:583:78: error: template argument 2 is invalid
warning: tectonic_xetex_layout@0.2.4:   583 |     LocalOpenPointer &operator=(std::unique_ptr<Type, decltype(closeFunction)> &&p) {
warning: tectonic_xetex_layout@0.2.4:       |                                                                              ^
warning: tectonic_xetex_layout@0.2.4: /usr/include/unicode/localpointer.h:599:59: error: template argument 2 is invalid
warning: tectonic_xetex_layout@0.2.4:   599 |     operator std::unique_ptr<Type, decltype(closeFunction)> () && {
warning: tectonic_xetex_layout@0.2.4:       |                                                           ^
warning: tectonic_xetex_layout@0.2.4: /usr/include/unicode/ubidi.h:579:1: note: invalid template non-type parameter
warning: tectonic_xetex_layout@0.2.4:   579 | U_DEFINE_LOCAL_OPEN_POINTER(LocalUBiDiPointer, UBiDi, ubidi_close);
warning: tectonic_xetex_layout@0.2.4:       | ^~~~~~~~~~~~~~~~~~~~~~~~~~~

error: failed to run custom build command for `tectonic_xetex_layout v0.2.4 (/build/tectonic/src/tectonic-tectonic-0.15.0/crates/xetex_layout)`

Caused by:
  process didn't exit successfully: `/build/tectonic/src/tectonic-tectonic-0.15.0/target/release/build/tectonic_xetex_layout-2d264a57173811f7/build-script-build` (exit status: 1)