See https://github.com/marketplace/actions/skip-duplicate-actions for a list of non-breaking changes.
Set concurrent_skipping to one of the values that are described in the README, or omit it if you do not want any concurrent skipping functionality.
If you used skip_concurrent_trigger, then you should replace it with something like the following line:
do_not_skip: '["pull_request", "workflow_dispatch", "schedule"]'