fix: cleanup old code for "record changes" session feature

had some tests failing, and one thing led to another.. apparenty we
still had support for some pretty old sqlalchemy so no need to keep
that around.

fix: refactor code so most things work without sqlalchemy

also refactor tests to help ensure that remains true

Make explicit which python versions are supported

as of writing, all of 3.6 thru 3.11

in practice i don't know of anyone running 3.7 so that may get dropped
sooner than later. unfortunately there are still a couple of 3.6 apps
but after those are upgraded probably the minimum supported version
will become 3.8

Overhaul the tox config

per lessons learned in wuttjamaican

also remove old reference to init.d scripts in manifest

Remove python2 stuff from `tox.ini`

thankfully no reason to test that anymore

Use `pytest` instead of `nosetests` for tox python 2.7

if this works okay then will update others