Error while installing with pip

It seems there is an error with Cython while installing g6k with pip:
$ pip install git+https://github.com/fplll/g6k.git 
Collecting git+https://github.com/fplll/g6k.git
  Cloning https://github.com/fplll/g6k.git to /tmp/pip-req-build-rb06fs9b
  Running command git clone --filter=blob:none --quiet https://github.com/fplll/g6k.git /tmp/pip-req-build-rb06fs9b
  Resolved https://github.com/fplll/g6k.git to commit 0643c78726983223f62402b4986bf21a2486b1c3
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
  error: subprocess-exited-with-error

  × Getting requirements to build wheel did not run successfully.
  │ exit code: 1
  ╰─> [20 lines of output]
      Traceback (most recent call last):
...
 get_requires_for_build_wheel
          return hook(config_settings)
                 ^^^^^^^^^^^^^^^^^^^^^
        File "/tmp/pip-build-env-6hn25xae/overlay/lib/python3.12/site-packages/setuptools/build_meta.py", line 325, in get_requires_for_build_wheel
          return self._get_build_requires(config_settings, requirements=['wheel'])
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/tmp/pip-build-env-6hn25xae/overlay/lib/python3.12/site-packages/setuptools/build_meta.py", line 295, in _get_build_requires
          self.run_setup()
        File "/tmp/pip-build-env-6hn25xae/overlay/lib/python3.12/site-packages/setuptools/build_meta.py", line 487, in run_setup
          super().run_setup(setup_script=setup_script)
        File "/tmp/pip-build-env-6hn25xae/overlay/lib/python3.12/site-packages/setuptools/build_meta.py", line 311, in run_setup
          exec(code, locals())
        File "<string>", line 30, in <module>
      ModuleNotFoundError: No module named 'Cython'
      [end of output]

  note: This error originates from a subprocess, and is likely not a problem with pip.
error: subprocess-exited-with-error

× Getting requirements to build wheel did not run successfully.
│ exit code: 1
╰─> See above for output.

note: This error originates from a subprocess, and is likely not a problem with pip.
The installation from the source works fine on the same system.
fplll / g6k

Error while installing with pip #127
