Install fails with Python-3.7 (PyYAML==3.11 doesn't build)

[sphakka]

It looks like PyYAML==3.11 is not compatible with Python-3.7 (already reported) which makes the whole install fail:

$ pip install --user apidoc
...
    ext/_yaml.c:20867:13: error: ‘PyThreadState’ {aka ‘struct _ts’} has no member named ‘exc_traceback’; did you mean ‘curexc_traceback’?
    20867 |     tstate->exc_traceback = local_tb;
          |             ^~~~~~~~~~~~~
          |             curexc_traceback
    error: command 'gcc' failed with exit status 1
    
    ----------------------------------------
  Rolling back uninstall of PyYAML
...
Command "/usr/bin/python -u -c "import setuptools, tokenize;__file__='/tmp/pip-install-5xjm58jn/PyYAML/setup.py';f=getattr(tokenize, 'open', open)(__file__);code=f.read().replace('\r\n', '\n');f.close();exec(compile(code, __file__, 'exec'))" install --record /tmp/pip-record-pe7fhm9r/install-record.txt --single-version-externally-managed --compile --user --prefix=" failed with error code 1 in /tmp/pip-install-5xjm58jn/PyYAML/

See attached log.

As mentioned in the upstream bug report, newer PyYAML versions are OK. Indeed, setting 'PyYAML>=3.11' (I have latest v5.1.2) in apidoc's requirements, makes the installation go through correctly :-)