flatpak-pip-checker should parse python_version synatx in requirements file

[bbhtt]

flatpak-builder version

1.3.3

Linux distribution and version

Fedora 38

Affected flatpak-builder tool

pip/flatpak-pip-generator

flatpak-builder tool cli args

NA

Source repository URL

NA

Flatpak-builder manifest URL

NA

Description

Pip checker should parse python_version in requirements file:

dataclasses == 0.8; python_version < "3.7"

and skip downloading a package if the package is not available for a specified python version.

[bbhtt]

Since, the versions of python included in manifest or runtime are already known beforehand, as a temporary solution --ignore-pkg can be used to skip those lines in requirements.txt #364