Error when installing with pip (Python 3.9)

[blwh]

Pip throws errors when trying to install gcMapExplorer on Python 3.9. The main error is

  gcMapExplorer/lib/ccmapHelpers.c: In function ‘__Pyx_modinit_type_init_code’:
  gcMapExplorer/lib/ccmapHelpers.c:6752:85: error: ‘PyTypeObject’ {aka ‘struct _typeobject’} has no member named ‘tp_print’
   6752 |   __pyx_type_13gcMapExplorer_3lib_12ccmapHelpers___pyx_scope_struct__make_smooth_map.tp_print = 0;
        |                                                                                     ^

The program builds and installs fine locally. I am guessing there is some cached pre-compiled version that is being used, but --no-cache-dir does not work.