Release v7.1.14

• dh drop guest from student attendance so disabling acedemic user disables all school doctypes (#6974)
• [fix] on advance payment entry cancellation delink invoice and pyament entry references
• Update update_missing_salary_component_type.py
• Updated modified_datetime in production planning tool
• [minor] fixes in validate selling price
• [Fix] Filters to get employee in Payroll
• [Fix]Product thumbnail in Shopping Cart
• [test-case] test cases for delinking advance payments
• [fix] on jv cancel remove linkings from advance table of Sales/Purchase Invoice
• [Fix] Payment entry, exchange rate is not set properly