Python install fail

[E3D3]

I followed the instructions for the installation with Python 3.9 (on Devuan Chimarea) but got error messages during the last step:
pip3 install -f 'https://synesthesiam.github.io/prebuilt-apps/' -f 'https://download.pytorch.org/whl/cpu/torch_stable.html' larynx

Below a part of the error output:

...
...
Building wheels for collected packages: python-crfsuite
  Building wheel for python-crfsuite (setup.py) ... error
  error: subprocess-exited-with-error

 × python setup.py bdist_wheel did not run successfully.
  │ exit code: 1
  ╰─> [287 lines of output]
...
...
pycrfsuite/_pycrfsuite.cpp:4:10: fatal error: Python.h: No such file or directory
          4 | #include "Python.h"
            |          ^~~~~~~~~~
      compilation terminated.
      error: command '/usr/bin/x86_64-linux-gnu-gcc' failed with exit code 1
      [end of output]

note: This error originates from a subprocess, and is likely not a problem with pip.
  ERROR: Failed building wheel for python-crfsuite
  Running setup.py clean for python-crfsuite
Failed to build python-crfsuite
...
...
Running setup.py install for python-crfsuite ... error
  error: subprocess-exited-with-error
  
  × Running setup.py install for python-crfsuite did not run successfully.
  │ exit code: 1
  ╰─> [289 lines of output]
...
...
pycrfsuite/_pycrfsuite.cpp:4:10: fatal error: Python.h: No such file or directory
          4 | #include "Python.h"
            |          ^~~~~~~~~~
      compilation terminated.
      error: command '/usr/bin/x86_64-linux-gnu-gcc' failed with exit code 1
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: legacy-install-failure

× Encountered error while trying to install package.
╰─> python-crfsuite

note: This is an issue with the package mentioned above, not pip.
hint: See above for output from the failure.

[jn64]

fatal error: Python.h: No such file or directory

You are missing Python headers. Install the Python 3 dev package for your distro, some examples here.

[E3D3]

Thanks, but I have the Python 3 dev package installed so guess that maybe I do something wrong and will try it again, later.