Remove unnecessary config since it matches the default value

Author: trask

.github/workflows/issue-management-stale-action.yml

@@ -65,4 +65,3 @@ jobs:
           stale-pr-message: >
             This PR has been labeled as stale due to lack of activity.
             It will be automatically closed if there is no further activity over the next 14 days.
-          exempt-draft-pr: false