Suggestion: make ezgb + git-bug optional dependencies

Hello,

I'd like to suggest that ezgb and git-bug become optional dependencies, essentially like textual is an optional dependency today. The reason is that by default "b4 bugs" prints:

The TUI requires the textual library.
Install it with: pip install b4[tui]

which gives me idea it's built around using the textual dependency. git-bug also seems like a fairly large dependency for a feature that doesn't really appear related to patch management in public-inbox archives, and that it's about a different workflow entirely (tracking bugs).

I took over packaging of b4 in Gentoo and found one unit test that failed because it couldn't import ezgb._cli (this was src/tests/test_packaging.py::test_public_modules_import_without_textual). To fix this test, I've packaged git-bug and ezgb, and am about to update the b4-0.16.0 package spec to require ezgb. In the process, I got the idea that maybe it would make sense to have these dependencies be optional.

All the best,
-- Thomas

This makes sense. I've added it to master, but I don't really want to backport it to 0.16 to minimize the churn in the stable branch.

-K