Switch pre-commit update workflow to use conda; various small changes

[altheaden]

This PR incorporates the changes in @xylar's E3SM-Project/mache#277 PR. I've also made a few changes:

1. reviewers are now stored in a string variable called REVIEWERS which is defined with the other env variables already included in the workflow
2. the python version has been updated from 3.10 to 1.13
3. I've added @andrewdnolan to the list of Dependabot reviewers as well as the pre-commit reviewers list

@xylar Review checklist:

• Add @andrewdnolan as maintainer (if he isn't already)

Checklist

• Testing comment in the PR documents testing used to verify the changes

[xylar]

Thanks @altheaden ! Let's see how it goes in an hour and a half!