ci: remove -X theirs from cherry-pick in checkout-pr script

Using a merge strategy only risks confusion when the merge leads to code being removed when it shouldn‘t be. Therefore, it‘s better to report a merge conflict and have the PR author resolve it manually.

scripts/checkout-pr.sh

@@ -8,7 +8,7 @@ git fetch pr "$PR_HEAD_REF"
 
 # Import changes from the PR into the current branch without committing
 BASE_COMMIT=$(git merge-base HEAD "pr/$PR_HEAD_REF")
-git cherry-pick -n "$BASE_COMMIT..pr/$PR_HEAD_REF" -X theirs
+git cherry-pick -n "$BASE_COMMIT..pr/$PR_HEAD_REF"
 
 # List the affected files for debugging purposes
 git diff --name-status --staged