[OU-ADD] stock_inventory_preparation_filter: Migration script

We recover these columns from standard Odoo if the exist.

stock_inventory_preparation_filter/migrations/13.0.1.0.0/post-migration.py

@@ -0,0 +1,30 @@
+# Copyright 2020 Tecnativa - Sergio Teruel
+# License LGPL-3.0 or later (https://www.gnu.org/licenses/lgpl).
+
+from openupgradelib import openupgrade
+
+
+def convert_m2o_to_x2m_fields(env):
+    categ_column = openupgrade.get_legacy_name("category_id")
+    if openupgrade.column_exists(env.cr, categ_column):
+        openupgrade.m2o_to_x2m(
+            env.cr,
+            env["stock.inventory"],
+            "stock_inventory",
+            "categ_ids",
+            categ_column,
+        )
+    lot_column = openupgrade.get_legacy_name("lot_column")
+    if openupgrade.column_exists(env.cr, lot_column):
+        openupgrade.m2o_to_x2m(
+            env.cr,
+            env["stock.inventory"],
+            "stock_inventory",
+            "lot_ids",
+            openupgrade.get_legacy_name("lot_id"),
+        )
+
+
+@openupgrade.migrate()
+def migrate(env, version):
+    convert_m2o_to_x2m_fields(env)