Log Message:
Update to 3.1.0. From the changelog:

- Add `mob clean` command that removes orphan wip branches that might be
  a left over of someone else doing a `mob done`. This is especially
  helpful when using a lot of feature branches. If you call `mob clean`
  on an orphan wip branch, it will switch you to the base branch,
  falling back to main/master if the base branch does not exist.
- The values `squash`, `no-squash` and `squash-wip` for MOB_DONE_SQUASH
  can be set not only via env var, but now in the .mob configuration
  file as well.