Without the change `nlohmann_json` build on `gcc-13 `fails as:
In file included from <<NIX>>-gcc-13.0.0/include/c++/13.0.0/ext/alloc_traits.h:34,
from <<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/basic_string.h:39,
from <<NIX>>-gcc-13.0.0/include/c++/13.0.0/string:54,
from <<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/locale_classes.h:40,
from <<NIX>>-gcc-13.0.0/include/c++/13.0.0/locale:41,
from tests/src/unit-regression2.cpp:19:
<<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/alloc_traits.h: In instantiation of 'struct std::__allocator_traits_base::__rebind<my_allocator<unsigned char>, unsigned char, void>':
<<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/alloc_traits.h:94:11: required by substitution of 'template<class _Alloc, class _Up> using std::__alloc_rebind = typename std::__allocator_traits_base::__rebind<_Alloc, _Up>::type [with _Alloc = my_allocator<unsigned char>; _Up = unsigned char]'
<<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/alloc_traits.h:228:8: required by substitution of 'template<class _Alloc> template<class _Tp> using std::allocator_traits< <template-parameter-1-1> >::rebind_alloc = std::__alloc_rebind<_Alloc, _Tp> [with _Tp = unsigned char; _Alloc = my_allocator<unsigned char>]'
<<NIX>>-gcc-13.0.0/include/c++/13.0.0/ext/alloc_traits.h:126:65: required from 'struct __gnu_cxx::__alloc_traits<my_allocator<unsigned char>, unsigned char>::rebind<unsigned char>'
<<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/stl_vector.h:88:21: required from 'struct std::_Vector_base<unsigned char, my_allocator<unsigned char> >'
<<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/stl_vector.h:423:11: required from 'class std::vector<unsigned char, my_allocator<unsigned char> >'
tests/src/unit-regression2.cpp:807:63: required from here
<<NIX>>-gcc-13.0.0/include/c++/13.0.0/bits/alloc_traits.h:70:31: error: static assertion failed: allocator_traits<A>::rebind_alloc<A::value_type> must be A
70 | _Tp>::value,
| ^~~~~
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