Add functionality to the backup script to prune backup files according to certain criteria:
- For the current quarter (1/1 to 3/31, 4/1 to 6/30, 7/1 to 9/31, 10/1 to 12/31), keep daily backups
- For previous quarters, keep only the backup on the final day of the quarter, and delete all the rest
Add functionality to the backup script to prune backup files according to certain criteria: