21.42 Release Notes (Oct-21, 2021 Release)

Bug Fix

Title: Category de-duplication added for strategies recommending categories.
Summary: When recommending categories, we have added the de-duplication of categories to prevent the same category from displaying in the placement more than once.  
Jira: https://jira.richrelevance.com/jira/browse/ENG-21147
Complete: Y
Customer Facing: Y