Backport to branch(3.16) : Fix Action to assign reviewers for Dependabot PRs

[feeblefakie]

This is an automated request for a manual backport of the following:

• Original PR: Fix Action to assign reviewers for Dependabot PRs #2958
• Commit to backport: cb1cbaa

1. Resolve any conflicts that occur during the cherry-picking process.

git fetch origin &&
git checkout 3.16-pull-2958 &&
git cherry-pick --no-rerere-autoupdate -m1 cb1cbaaf2343b53804fe7e9f5543d0f3adf949be

2. Push the changes.
3. Merge this PR after all checks have passed.

Thank you!