[FIX] l10n_it_account_stamp: migration script for stamp lines

l10n_it_account_stamp/migrations/14.0.1.0.0/post-migration.py

@@ -0,0 +1,22 @@
+#  Copyright 2025 Sergio Zanchetta
+#  License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from openupgradelib import openupgrade
+
+
+@openupgrade.migrate()
+def migrate(env, version):
+    openupgrade.logged_query(
+        env.cr,
+        """
+        UPDATE account_move_line aml
+        SET
+            is_stamp_line = True
+        FROM account_move am
+        WHERE
+            aml.move_id = am.id AND
+            am.tax_stamp = True AND
+            aml.invoice_id is NULL AND
+            aml.display_type is NULL;
+    """,
+    )