devel/git-bug: Fix termui issue

Amended:

• Import upstream fix for termui [1] as mentioned here [2]. We can now _actually_ use 'git bug termui' without it indefinitely hanging.

[1]: https://github.com/nsf/termbox-go/commit/58d4fcbce2a7e6a3a48afbc6b7ec2a916ac33ee0
[2]: https://github.com/MichaelMure/git-bug/issues/387

PR: 246486
Submitted by: Lewis Cook <vulcan@wired.sh> (maintainer)