devel/got: update to 0.74

User-visible changes:

• add missing revoked_signers grammar to got.conf(5)
• add signer_id option to got.conf(5)
• move 'got init' command to 'gotadmin init'
• tog: implement global 'S' key map to switch split mode
• tog: implement +/- keymaps to resize the focussed split
• make 'tog log' error out in shallow Git repositories instead of hanging
• tog: enable moving to prev/next blame line in diff view
• histedit script: allow mesg command only after pick or edit commands