Branch "python3.8" requires python 3.9?

[Aruee]

Trying to run map-machine on my Ubuntu-LTS (which is a work machine, so I cannot upgrade the OS), I run into this issue when compiling the python 3.8 branch:

Installed /usr/lib/python3.8/site-packages/map_machine-0.1.5-py3.8.egg
Processing dependencies for map-machine==0.1.5
Searching for numpy>=1.18.1
Reading https://pypi.org/simple/numpy/
Downloading https://files.pythonhosted.org/packages/dd/2b/205ddff2314d4eea852e31d53b8e55eb3f32b292efc3dd86bd827ab9019d/numpy-1.26.2.tar.gz#sha256=f65738447676ab5777f11e6bbbdb8ce11b785e105f690bc45966574816b6d3ea
Best match: numpy 1.26.2
Processing numpy-1.26.2.tar.gz
Writing /tmp/easy_install-zbi8rzzp/numpy-1.26.2/setup.cfg
Running numpy-1.26.2/setup.py -q bdist_egg --dist-dir /tmp/easy_install-zbi8rzzp/numpy-1.26.2/egg-dist-tmp-zdd5jegj
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/setuptools-69.0.2-py3.8.egg/setuptools/sandbox.py", line 156, in save_modules
    yield saved
  File "/usr/local/lib/python3.8/dist-packages/setuptools-69.0.2-py3.8.egg/setuptools/sandbox.py", line 198, in setup_context
    yield
  File "/usr/local/lib/python3.8/dist-packages/setuptools-69.0.2-py3.8.egg/setuptools/sandbox.py", line 259, in run_setup
    _execfile(setup_script, ns)
  File "/usr/local/lib/python3.8/dist-packages/setuptools-69.0.2-py3.8.egg/setuptools/sandbox.py", line 46, in _execfile
    exec(code, globals, locals)
  File "/tmp/easy_install-zbi8rzzp/numpy-1.26.2/setup.py", line 22, in <module>
    version=__version__,
RuntimeError: Python version >= 3.9 required.

It just seems kind of odd that a branch that is specifically called python3.8 would require 3.9 to satisfy its numpy dependency?