Abrechnung wrong when new Miete in Vertrag #83
Description
Describe the bug
When a Mieter gets a new Vertragversion with a different Miete the Abrechnung of the previous year is wrong.
E.g. when the Grundmiete changes in 2023 the Abrechnung of 2022 is off by a few thousands.
To Reproduce
Change the Grundmiete of a Vertrag for the respective year and check the Abrechnung of the previous year.
Expected behavior
The Abrechnung of the previous year should not be changed.
The Abrechnung of the respective year should be correct.
Additional context
No Abrechnungen were harmed due to this error. It was found by accident and can be fixed before we need new Abrechnungen.