httplib2 dependency is going to support py3.7+ in 0.30 release, please test against master

[temoto]

i think this repo is important user of httplib2.
please see this change httplib2/httplib2@1a6ff78

this breaking change will be released as 0.30.0

if you must support py <3.7 lock down httplib2<0.30

otherwise please test against unreleased master with pip install -U https://github.com/httplib2/httplib2/archive/refs/heads/master.zip