gh: update to 2.17.0

- Add gh auth token
- Add flag to pr merge allowing the selection of the merge commit email
- Fix color output for non-256 color terminals
- surface merge conflicts in pr status
- Add header to the gpg-key list output
- Fix Ubuntu installation instructions for curl
- Fix missing text in "man gh-codespace-ssh"
- update formatting help
- add and use ConfirmDeletion in {label,repo} delete
- Add more help to "template" flags

(bsiegert)