Feature: Explicit dependency versions for each release

[yardasol]

Background and motivation

We should be able to download a release and set up the software environment with the exact versions of the dependencies in use at the time in case there are API changes to SaltProc's dependencies in the future

Description of idea

Each release should have an vx.x.x-environment.yml file that contains explicit min and max versions for each dependency in that releases environment.yml file.

Implementation details

I predict we will need to do the following:

• Create a workflow that, when the current draft release is published, creates the vx.x.x-environment.yml file described above.
• Add a a section in the User's Guide to let user's know that they can use this environment file and install from source if they run into trouble installing from conda-forge.

Potential snags

None I can think of.