Allows gpg to run for merge commands

[Neko-Box-Coder]

• PR Description This PR allows GPG to run for merge commands, previously it just hangs if GPG password is required in the CLI.

• Please check if the PR fulfills these requirements

• [x] Cheatsheets are up-to-date (run go generate ./...)
• [x] Code has been formatted (see here)
• [ ] Tests have been added/updated (see here for the integration test guide)
• [ ] Text is internationalised (see here)
• [x] Docs have been updated if necessary
• [x] You've read through your own file changes for silly mistakes etc

[Neko-Box-Coder]

Okay, I fixed the obvious ones that caused it to fail the tests.

But I can't figure out the tests that are failing now. To me, the changes should behave the same as before because I am just calling the logic in rebase.go in merge_and_rebase_helper.go instead. And nobody else is using the functions I am modifying except itself (rebase.go)

I can replicate the failing tests in sandbox mode but I am not too sure why. I probably need some help/pointers here since I am new to the codebase and golang is not main language