bindings: python: add misc build files to EXTRA_DIST

bindings: python: add misc build files to EXTRA_DIST

Several files are not being included in distro tarballs so the
functionality of the python build is limited compared to the repo. Add
them to EXTRA_DIST.

Fixes: d588a6a5928a ("bindings: python: standalone build tooling for tests")
Fixes: 72d2fa01a2c1 ("bindings: python: add script to generate sdist and wheels")
Fixes: 85089d0e40ac ("bindings: python: add pyproject.toml, pep 518")
Fixes: 389a966d4e61 ("bindings: python: move long_description into README.md")
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>