Update dependencies to satisfy safety check

Pyup.io's "safety" check failed on packages lxml, mako, and dparse.
None of these were explicit in our pyproject.toml file, but I modified
the entry to alembic, which was the package that required mako, then
ran poetry update to update the poetry.lock file.

To be honest, I'm not sure changing pyproject.toml file was needed
at all. I still don't fully understand how poetry works I guess. But,
everthing is "safe" now, and this merge request should now make it
through the CICD pipeline without further issue (fingers crossed).