* remove reference in comments to python3.6
* upgrade tox python env in script
* bump python version in example for completeness
* upgrade python version requirement in setup doc
* upgrade necessary python version in __init__.py
* upgrade python version in setup.py
* newsfragment
* drops refs to bionic and replace with focal
* bump refs to postgres 9.6 to 10
* fix hanging ci
* try installing tzdata first
* revert change made in b979f336
* ignore new random mypy error while debugging other error
* fix lint error for temporary workaround
* revert change to install list
* try passing env var
* export debian frontend var?
* move line and add comment
* bump pillow dependency
* bump lxml depenency
* install libjpeg-dev for pillow
* bump automat version to one compatible with py3.8
* add libwebp for pillow
* bump twisted trunk python version
* change suffix of newsfragment
* remove redundant python 3.7 checks
* lint
So that they render nicely in mdbook (see #10086), and so that we no longer have a mix of structured text languages in our documentation (excluding files outside of `docs/`).
Shay