Check basic state pension logic

It seems ```amount_in_data_year``` doesn’t depend on ```maximum_basic_sp```. It never goes to zero when assigning ```maximum_basic_sp``` to zero.

https://gist.github.com/vahid-ahmadi/dda76abf28799016491af40b474d0828

![Image](https://github.com/user-attachments/assets/bb28ab8c-4791-4791-97a6-a550c7e8fc8d)