setup: bump version numbers to current max

Based on 'pip freeze' before/after:

sed -i -e '/>=[^#]*$/s/, < [0-9.]\+//g' -e 's, == , >= ,g' setup.py dev_requirements.txt

Markdown 3.3 is a few months old could be bumped too ... but it change test
output due to
https://python-markdown.github.io/change_log/release-3.2/#codehilite-now-always-wraps-with-ltcodegt-tags
and can wait.

This is landing early in the development phase and will thus get good test
coverage.