conda update does not install non-pinned dependencies

[brynpickering]

Looks like there's an issue where conda/mamba/micromamba update ... won't actually update any defined dependencies that are unpinned. This is a problem as our latest implementation, moving from setup-micromamba to setup-miniconda (#26) uses this functionality.

The solution is to use mamba create --yes -n [env-name] to re-create the environment from scratch rather than updating the boilerplate environment that is created by setup-miniconda.