fix: posting_date for Sales Order should NOT be today but the from_date

[miteshpc]

PropMS/propms/lease_invoice.py

Line 58 in 5d6aecc

posting_date=today(),

For Sales Invoice and tax regulatory authority rules, it should be today() for Sales Invoice, but for Sales Order, it should be doc.from_date

[iphenelist]

The PR #48 solving the issue of Sales Order posting_date to be from doc.from_date