[FIX] survey_resource_booking: adapt to partner refactor

We need to adapt tests to OCA/calendar#110

TT45338

survey_resource_booking/tests/test_invite.py

@@ -32,7 +32,7 @@ def test_new_booking_survey_invitation(self):
         # Make sure RB gets surveyed as expected
         booking_f = Form(self.env["resource.booking"])
         booking_f.type_id = self.rbt
-        booking_f.partner_id = self.partner
+        booking_f.partner_ids.add(self.partner)
         booking_f.start = datetime(2021, 3, 1, 8)
         booking = booking_f.save()
         self.assertEqual(booking.state, "scheduled")