Release v7.1.21

• [Minor] Apply Salary Slip validation only if it is submitted
• [fix] email digest cache by frequency
• [fix] salary slip working days
• [Enhancement] Total row added for report builder
• [fix] test cases for customer credit
• [fix] currecny symbol for customer's total annual billing, total unpaid amount
• [Fix] Status of sales order and purchase order
• [Fix] lwp issue fixed for salary slip without salary structure
• Update project_wise_stock_tracking.json
• allow user to edit serial no for credit note, debit note
• [Fix] Fixed condition and formula issue in Salary Slip
• [fix] Project wise Stock Tracking is script report
• calc timesheet dates on validate not just submit