Describe the bug
env SHELL=cat git commit -m "test" runs git-hooks correctly, but gitui with a nonstandard shell doesn't

To Reproduce
0. go to repo with pre-commit hooks

1. env SHELL=cat gitui
2. create a commit
3. See error
4. see that env SHELL=cat git commit -m "test" works

Expected behavior
git-hooks should work even with a non-standard shell.

Screenshots

Context (please complete the following information):

• OS/Distro + Version: [e.g. macOS 10.15.5] Linux
• GitUI Version [e.g. 0.5] v0.27.0
• Rust version: [e.g 1.44] 1.83.0

Additional context
Add any other context about the problem here.
I think /bin/sh or git var GIT_SHELL_PATH should be used.
#2343 (comment)
We should probably do the same as in: GitoxideLabs/gitoxide@51bbb86

While this issue is a bit constructed, with SHELL=xonsh i have the problem that my pre-commit hooks do not get run. So this is a real problem users could be facing.