[ADD] copy paste module account_sub_accounts from version 16.0 and updated version to 18.0

account_sub_accounts/models/__init__.py

@@ -0,0 +1,2 @@
+from . import res_parter
+from . import account_move_line

account_sub_accounts/models/account_move_line.py

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+from odoo import fields, models
+
+
+class AccountMoveLine(models.Model):
+    _inherit = "account.move.line"
+
+    sub_account_customer = fields.Char(
+        string="Custommer sub-account",
+        related="partner_id.sub_account_customer"
+    )
+
+    sub_account_supplier = fields.Char(
+        string="Supplier sub-account",
+        related="partner_id.sub_account_supplier"
+    )

account_sub_accounts/models/res_parter.py

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+from odoo import fields, models
+
+
+class Partner(models.Model):
+    _inherit = "res.partner"
+
+    sub_account_customer = fields.Char(string="Custommer sub-account")
+    sub_account_supplier = fields.Char(string="Supplier sub-account")