Release v12.21.0

• chore: Added change log for v12.21.0
• fix: timeout error while loading warehouse tree
• fix: update item level cost center from POS profile (#25612)
• fix: check for None in item.schedule_date before setting
• fix: Employee Separation (#25504)
• fix: total stock summary report not working
• fix: issue in project custom status (#25453)
• feat(italy): add document type field for e-invoicing (#25420)
• fix: incorrect qty calculated for sub-contracted raw materials in purchase receipt
• fix: remove invalid changes added due to merge conflict (#25405)
• fix: remove invalid changes added due to merge conflict (#25437)
• fix: filter using purpose, make requested changes (#25388)
• fix: change subcontracted item display (#25426)
• Update init.py
• fix: Test case for GSTR 3b report
• fix: Purchase from registered composition dealer
• fix: RCM rounding precision
• fix: can't multiply sequence by non-int of type 'float' (#25385)
• fix(e-invoicing): variable scoping (#25368)