Test, debug and dev requires a narrower set of Python version.

[SebMouren]

maturin, a dependency, and, at least, one of its own dependencies limit the versions of Python to <=3.9:
puccinialin package is an import of maturin and has this requirement.
What do you think about a note on the readme about that, or on the fact that development has different requirements?

[kitao]

To clarify, puccinialin requires Python >= 3.9, not <= 3.9.
And because cargo is already a mandatory requirement for building Pyxel, this package is not actually needed in our case.