Date v/s Payment date

The payment date field is not used by Firefly to generate reports. (https://github.com/orgs/firefly-iii/discussions/7837)

Also, Splitwise sends 6am for the `exp.getDate()` which after getting converted to the timezone ends up being the previous day. This should be fixed with a truncating generation or generate a date for UTC in the middle of the day that cannot get rolled over.