Python 3.x bindings support which versions, exactly?

[Ralph Seichter]

Hello,

having examined the source code, I assume that Notmuch's Python bindings
should support Python 3.x for any given 'x'. However, reading the Travis
logs at https://travis-ci.org/notmuch/notmuch and .travis.yml, the CI
tests apparently run on Ubuntu 18.04 and use only Python 3.6.

While I hope there won't be any problems with Python 3.7, 3.8 and 3.9,
I wanted to ask here first if anybody has tested this yet?

-Ralph