#to_s
#to_str
Fixes: Error: no implicit conversion of GitRepository into String when doing `brew pr-pull --autosquash`. See [1]. I contemplated implementing only `#to_s`, but we've historically used these as `Pathname`s, and `Pathname` defines `#to_str`. [1] https://github.com/Homebrew/homebrew-core/actions/runs/4784638305/jobs/8506369135#step:10:54