[python-cffi] Version number for the `notmuch2` bindings

[Frank LENORMAND]

Hi,

The original Python bindings follow the entire repository's version
number[1]. The new Python bindings use `0.1`[2].

The Debian package[3] follows the same version number as well, but
it's starting to confuse maintainers of packages for other environments
(e.g. Pypi[4]), who use `0.1` because that's what's in the code.

Which one is it?

Thanks!

[1] https://git.notmuchmail.org/git?p=notmuch;a=blob;f=bindings/python/setup.py;h=d986f0c6651ee14ef9b4607b7668b82acde7fbdc;hb=HEAD#l33
[2] https://git.notmuchmail.org/git?p=notmuch;a=blob;f=bindings/python-cffi/setup.py;h=37918e3d2cdb3b7bcf0a3e3db860bfab5bd1b0db;hb=HEAD#l6
[3] https://packages.debian.org/en/experimental/main/python3-notmuch2
[4] https://github.com/weilbith/notmuch-python-bindings/issues/1#issuecomment-646054040

Regards,
-- 
Frank LENORMAND