Update app build and env (pt 3)

[bdewilde]

changes

• updates various dependencies' versions to new-ish but not brand new, pushing things out of "so old it's hard to find documentation" territory and into "a major version or so back, but still relatively modern" -- in practice, this typically means releases around 2020
• tweaks package version to 1.1-dev, which we'll increment to 1.1 when all these build stabilization, CI, etc. efforts complete

yet TODO in a follow-up PR:

• update db-focused dependencies (e.g. sqlalchemy, alembic)
• update data validation/parsing deps (e.g. marshmallow, webargs)
• update lower-level system deps (e.g. redis, gunicorn?)

questions

have i accidentally messed anything up? the package builds and i've ensured that it runs my local, manual "end to end" test case, but this doesn't cover all pathways. just holler if you see something obvious. otherwise, we'll have to root them out when we implement proper tests.

[samanz]

We probably want to "blacken" this repo sooner than later to make sure our merge requests are compatible later on.

[bdewilde]

@samanz planning to black code immediately after i add some baseline unit testing -- which is coming up next, so the plan is "soon" :)