[PATCH] Update tox.ini for python3.8 and fix pypy3.6

[David Bremner]

Floris Bruynooghe <flub at devork.be> writes:

>  [testenv]
>  deps =
> @@ -14,3 +14,6 @@ commands = pytest --cov={envsitepackagesdir}/notmuch2 {posargs}
>  
>  [testenv:pypy35]
>  basepython = pypy3.5
> +
> +[testenv:pypy36]
> +basepython = pypy3.6

I'm not an expert, but should python 3.7 and python 3.8 have similar
clauses? Or do they work by default?

d