Fix "no merge base" failures in ruff tests
Let's make sure the full repository is cloned to avoid errors like the following:
git diff --name-only e453e2cbd65db3b7eb59fbd2f5efef712b34fef4...
fatal: e453e2cbd65db3b7eb59fbd2f5efef712b34fef4...HEAD: no merge base
closes #20408 (closed)
Edited by intrigeri