fix(ci): drop the git gem pin now that danger 9.6.1 is out

Summary

Removes the root Gemfile added in !3637 (merged). It existed only to hold the git gem below 5.0.0 — the upstream incompatibility it worked around was fixed in danger 9.6.1, published to rubygems 2026-07-29 03:28 UTC.

Background

danger 9.6.0 reopened Git::Base as a class to install its merge-base override. git 5.0.0 (published 2026-07-28 14:24 UTC) redefined Git::Base as a compatibility module included in Git::Repository, so the reopen raised at load:

danger-9.6.0/lib/danger/scm_source/git_repo.rb:196:in `<module:Git>':
  Base is not a class (TypeError)

danger#1550 fixed this by branching on the type, verified in the shipped 9.6.1 gem at lib/danger/scm_source/git_repo.rb:207:

# Git::Base became a compatibility module included in Git::Repository in git 5.0.
if Git::Base.kind_of?(Class)
  Git::Base.prepend(Danger::GitRepo::MergeBase)
else
  Git::Repository.prepend(Danger::GitRepo::MergeBase)
end

Why this is a deletion and not a version bump

danger was never pinned here. The Gemfile listed gitlab-dangerfiles unversioned and there is no Gemfile.lock, so bundler re-resolves at job runtime and 9.6.1 is already in use. The only constraint this file still imposes is on git:

	danger	git
Before	9.6.1	4.4.0, held by the pin
After	9.6.1	5.0.0

Both work — 9.6.1 handles either. Removing the file just releases a constraint danger no longer needs.

Nothing else references the Gemfile: no .gitignore entry, no CI job, no Renovate config. The component's before_script short-circuit ([[ -f "Gemfile" ]] || bundle add gitlab-dangerfiles) resumes generating its own, which is the pre-!3637 behaviour.

No bump of danger-review@2.1.0 is needed, so this also avoids pulling in that component's unreleased main drift.

Follow-up

danger-review!22 (pin git < 5.0.0 in the component's generated Gemfile) is now obsolete and would hold consumers back unnecessarily — worth closing in favour of 9.6.1.

Test plan

• danger-review passes on this MR's pipeline. This is the real check: with the Gemfile gone the job exercises the auto-generate path and must resolve danger 9.6.1 + git 5.0.0.

🤖 Generated with Claude Code