fw: Doesn't work with GPG SSH agent on macOS

I use gpg-agent (GnuPG) 2.2.15 to do my SSH authentication, configured to prompt via GUI, and requiring me to press my Yubikey to finish the request.

When I use fw sync, it stops at Apr 11 14:41:40.416 DEBG Update project remotes, path: "/Users/liamdawson/w/...", exists: true, git: git@github.com:..., command: sync, and Activity Monitor shows fw using ~80% CPU. However, after workon git hooks seem to work fine, much like normally using git on my CLI. For example, I can fw sync -n, ctrl+c, cd project_directory and then git fetch origin --prune successfully.

I think adding a workaround that shells out to the native git executable (instead of doing it in-process via the libgit2 bindings) would help me in this situation.