Add micromamba version to cache key?

[jonashaag]

If you change the Micromamba version (implicit update due to new release, explicit update to due version pin) any environment cached with a previous Micromamba version is restored.

I wonder if we should make the cache dependent on the Micromamba version because there might be bug fixes in newer versions that affect the environment

[pavelzw]

Yes, that sounds reasonable 👍

[bhperry]

Speaking of.... this issue became a whole lot more painful to deal with because of this

[pavelzw]

it would probably be easiest to just include the sha256 of the micromamba executable in the cache key. PRs are welcome :)