Fix TypeError when force_updater receives git commit SHA instead of Version

[Copilot]

What are you trying to accomplish?

Fixes TypeError: T.cast: Expected type Dependabot::Version, got type String when updating git dependencies.

For git dependencies, latest_version returns commit SHAs (String) from methods like git_commit_checker.head_commit_for_current_branch. The force_updater expects Gem::Version objects and validates this constraint. Git dependencies bypass version resolution entirely—they track commits, not semantic versions—making the full unlock path inapplicable.

Anything you want to highlight for special attention from reviewers?

Added guards to short-circuit before force_updater invocation:

• latest_version_resolvable_with_full_unlock? returns false for git dependencies
• updated_dependencies_after_full_unlock returns [] for git dependencies

This follows the existing pattern for git dependency handling (see lowest_resolvable_security_fix_version line 47).

Alternative considered: Modify ForceUpdater to accept String types. Rejected because full unlock semantics don't apply to git dependencies—they don't have version constraints to unlock.

How will you know you've accomplished your goal?

Added test coverage for both methods with git dependencies returning commit SHAs. Tests verify no TypeError is raised and appropriate values are returned.

All changes pass Sorbet type checking, RuboCop validation, and CodeQL security analysis.

Checklist

• I have run the complete test suite to ensure all tests and linters pass.
• I have thoroughly tested my code changes to ensure they work as expected, including adding additional tests for new functionality.
• I have written clear and descriptive commit messages.
• I have provided a detailed description of the changes in the pull request, including the problem it addresses, how it fixes the problem, and any relevant details about the implementation.
• I have ensured that the code is well-documented and easy to understand.

💬 We'd love your input! Share your thoughts on Copilot coding agent in our 2 minute survey.