Compilation fails in c++20

[vvkphys]

The code does not work with C++20.

Apptainer> make
[ 0%] Built target atlas_tests
[ 0%] Built target Package_bjoern-andres-graph
[ 11%] Building CXX object GraphTest/CMakeFiles/GraphTestLib.dir/src/GraphTestAlg.cxx.o
In file included from /srv/build/_deps/bjoern-andres-graph-src/include/andres/graph/detail/graph.hxx:6,
from /srv/build/_deps/bjoern-andres-graph-src/include/andres/graph/graph.hxx:17,
from /srv/athena-graph/GraphTest/src/GraphTestAlg.cxx:4:
/srv/build/_deps/bjoern-andres-graph-src/include/andres/random-access-set.hxx: In instantiation of 'class andres::RandomAccessSet<andres::graph::Adjacency<> >':
/srv/build/_deps/bjoern-andres-graph-src/include/andres/graph/detail/graph.hxx:30:23: required from here
/srv/build/_deps/bjoern-andres-graph-src/include/andres/random-access-set.hxx:35:49: error: no type named 'const_reference' in 'class std::allocator<andres::graph::Adjacency<> >'
35 | typedef typename Allocator::const_reference const_reference;
| ^~~~~~~~~~~~~~~
/srv/build/_deps/bjoern-andres-graph-src/include/andres/graph/detail/graph.hxx:63:5: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
63 | value_type operator*() const;
| ^~~~~~~~~~
/srv/build/_deps/bjoern-andres-graph-src/include/andres/graph/detail/graph.hxx:64:5: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
64 | value_type operator[](const std::size_t j) const;
| ^~~~~~~~~~
/srv/build/_deps/bjoern-andres-graph-src/include/andres/graph/detail/graph.hxx:160:8: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
160 | inline typename IteratorHelper::value_type
| ^~~~~~~~
/srv/build/_deps/bjoern-andres-graph-src/include/andres/graph/detail/graph.hxx:171:8: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
171 | inline typename IteratorHelper::value_type
| ^~~~~~~~
make[2]: *** [GraphTest/CMakeFiles/GraphTestLib.dir/build.make:76: GraphTest/CMakeFiles/GraphTestLib.dir/src/GraphTestAlg.cxx.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:320: GraphTest/CMakeFiles/GraphTestLib.dir/all] Error 2
make: *** [Makefile:136: all] Error 2

If you check, the type in question was removed with C++20.

https://en.cppreference.com/w/cpp/memory/allocator

Is it possible to make this code working with C++20?

Best regards,
Vadim