Merge branch 'fs/ssh-signing-key-lifetime'

Extend the signing of objects with SSH keys and learn to pay attention to the key validity time range when verifying. * fs/ssh-signing-key-lifetime: ssh signing: verify ssh-keygen in test prereq ssh signing: make fmt-merge-msg consider key lifetime ssh signing: make verify-tag consider key lifetime ssh signing: make git log verify key lifetime ssh signing: make verify-commit consider key lifetime ssh signing: add key lifetime test prereqs ssh signing: use sigc struct to pass payload t/fmt-merge-msg: make gpgssh tests more specific t/fmt-merge-msg: do not redirect stderr