[BUG]: ASAN reports that allocated ptr is not deallocated properly.

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Problem description

Hi, ASAN reports that https://github.com/pybind/pybind11/blob/6493f496e30c80f004772c906370c8f4db94b6ec/include/pybind11/detail/internals.h#L498-L508 allocated ptr variable in internals.h:504 is not deallocated properly when calling finalize_interpreter few times.
ASAN report:

==497630==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 8 byte(s) in 1 object(s) allocated from:
    #0 0x7f80838e8587 in operator new(unsigned long) ../../../../src/libsanitizer/asan/asan_new_delete.cc:104
    #1 0x557df8f07925 in pybind11::detail::local_internals::local_internals() /home/vmcs/projects/scanner/vendor/pybind11/include/pybind11/detail/../detail/internals.h:504
    #2 0x557df8f07925 in pybind11::detail::get_local_internals() /home/vmcs/projects/scanner/vendor/pybind11/include/pybind11/detail/../detail/internals.h:514
    #3 0x557df8f07925 in pybind11::finalize_interpreter() /home/vmcs/projects/scanner/vendor/pybind11/include/pybind11/embed.h:203

Reproducible example code

int test_lib() {
  py::initialize_interpreter();
  try {
    py::object mainScope = py::module::import("__main__").attr("__dict__");
    py::exec( "print('hello')", mainScope);
  } catch(pybind11::error_already_set const& ex) {
    std::cerr << " [PYBIND11 ERROR] " << ex.what() << std::endl;
    return EXIT_FAILURE;
  }
  py::finalize_interpreter();
  return 0;
}
int main() {
  for(int i = 0; i < 10; i ++) {
    test_lib();
  }
}

Start with the local_internals allocation at include/pybind11/detail/internals.h:498-508 and the finalize_interpreter path in include/pybind11/embed.h:203. Run the provided repeated initialize/finalize example under ASAN; done means the leak report no longer identifies the allocated pointer after ten interpreter cycles.