AttributeError: cython_sources when installing package

Question

I'm trying to download a package named postcards, but apparently there is something that won't be allowed to get downloaded. If i have understood, there is something called PyYAml that does not get the necessary requirements, and it would be linked with Cython... I have read on others posts that I could maybe solve the problem by using another version of cython (here:https://discuss.python.org/t/getting-requirements-to-build-wheel-did-not-run-successfully-exit-code-1/30365), but I don't know how to do this and even if it's the right solution. If anyone could help, I'd be glad ! (As you may have seen, I'm not a professional) Here's the code :

Collecting PyYAML==6.0 (from postcards)
  Using cached PyYAML-6.0.tar.gz (124 kB)
  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
  ╰─> [54 lines of output]
      running egg_info
      writing lib\PyYAML.egg-info\PKG-INFO
      writing dependency_links to lib\PyYAML.egg-info\dependency_links.txt
      writing top-level names to lib\PyYAML.egg-info\top_level.txt
      Traceback (most recent call last):
        File "C:\Users\sdalh\AppData\Local\Programs\Python\Python312\Lib\site-packages\pip\_vendor\pyproject_hooks\_in_process\_in_process.py", line 353, in <module>
          main()
        File "C:\Users\sdalh\AppData\Local\Programs\Python\Python312\Lib\site-packages\pip\_vendor\pyproject_hooks\_in_process\_in_process.py", line 335, in main
          json_out['return_val'] = hook(**hook_input['kwargs'])
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "C:\Users\sdalh\AppData\Local\Programs\Python\Python312\Lib\site-packages\pip\_vendor\pyproject_hooks\_in_process\_in_process.py", line 118, in get_requires_for_build_wheel
          return hook(config_settings)
                 ^^^^^^^^^^^^^^^^^^^^^
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\build_meta.py", line 355, in get_requires_for_build_wheel
          return self._get_build_requires(config_settings, requirements=['wheel'])
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\build_meta.py", line 325, in _get_build_requires
          self.run_setup()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\build_meta.py", line 341, in run_setup
          exec(code, locals())
        File "<string>", line 288, in <module>
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\__init__.py", line 103, in setup
          return distutils.core.setup(**attrs)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\_distutils\core.py", line 185, in setup
          return run_commands(dist)
                 ^^^^^^^^^^^^^^^^^^
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\_distutils\core.py", line 201, in run_commands
          dist.run_commands()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\_distutils\dist.py", line 969, in run_commands
          self.run_command(cmd)
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\dist.py", line 989, in run_command
          super().run_command(command)
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\_distutils\dist.py", line 988, in run_command
          cmd_obj.run()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\command\egg_info.py", line 318, in run
          self.find_sources()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\command\egg_info.py", line 326, in find_sources
          mm.run()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\command\egg_info.py", line 548, in run
          self.add_defaults()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\command\egg_info.py", line 586, in add_defaults
          sdist.add_defaults(self)
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\command\sdist.py", line 113, in add_defaults
          super().add_defaults()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\_distutils\command\sdist.py", line 251, in add_defaults
          self._add_defaults_ext()
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\_distutils\command\sdist.py", line 336, in _add_defaults_ext
          self.filelist.extend(build_ext.get_source_files())
                               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "<string>", line 204, in get_source_files
        File "C:\Users\sdalh\AppData\Local\Temp\pip-build-env-s0tc86go\overlay\Lib\site-packages\setuptools\_distutils\cmd.py", line 107, in __getattr__
          raise AttributeError(attr)
      AttributeError: cython_sources
      [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.

I tried to use specific versions of pip, to use other versions of cython, to pip install e- (not sure what it really changes, if I have well understood -e is for editable mode) or to copy basically code lines I found on forums discussing about the same problem...