[MIG] contract_variable_quantity: Migration to 14.0

[UPD] Update contract_variable_quantity.pot

[UPD] README.rst

contract_variable_quantity/tests/test_contract_variable_quantity.py

@@ -3,15 +3,16 @@
 # Copyright 2018 ACSONE SA/NV
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
-import odoo.tests
 from odoo import exceptions
+from odoo.tests.common import SavepointCase
 
 
-@odoo.tests.at_install(False)
-@odoo.tests.post_install(True)
-class TestContractVariableQuantity(odoo.tests.HttpCase):
+class TestContractVariableQuantity(SavepointCase):
+    at_install = False
+    post_install = True
+
     def setUp(self):
-        super(TestContractVariableQuantity, self).setUp()
+        super().setUp()
         self.partner = self.env["res.partner"].create({"name": "Test partner"})
         self.product = self.env["product.product"].create({"name": "Test product"})
         self.contract = self.env["contract.contract"].create(