Update release process to use conda-forge

[forsyth2]

Update GitHub Actions and https://e3sm-project.github.io/zstash/_build/html/main/dev_guide/release.html#releasing-on-anaconda to reflect the new conda-forge process (see conda-forge/staged-recipes#21883).

From @xylar: we would need to remove the GitHub actions that make the build for the e3sm anaconda channel. Then, you would change the sections about anaconda to instead refer to waiting for a bot PR to come up automatically on conda-forge after the GitHub release. A maintainer would then update the dependencies on conda-forge to match the conda/meta.yaml file for the GitHub release and merge the conda-forge PR.

[xylar]

It is time to make these changes (before the next release), now that there is a zstash feedstock:
https://github.com/conda-forge/zstash-feedstock/