Automate dependency update checks for our packages

[tsibley]

Bioconda's "autobump" tooling will automatically update recipe versions for many packages and submit PRs on our behalf. This process runs regularly.

It has the ability to check for upstream dependency changes for Python packages, but it's not enabled by default because it would currently require running setup.py for all packages.

We could configure a scheduled workflow in this repo (our own) to enable dependency checking for just our packages and submit PRs ourselves, using the same tooling. It'd be nice, although not strictly necessary, to avoid duplicate PRs by opting out of the regular autobump process if possible.

[tsibley]

This is an alternative approach to what we could accomplish without manual intervention via automatic dep inclusion, which seems unlikely to be integrated by upstream.