Finish sprint dates aren't working for 2023

[ktohalloran]

The repo currently counts weeks assuming that Sundays are a part of the previous week. However, this is not how Outlook's week counting and therefore our own week counting worked in 2023. This is due to the fact that 2023 started on a Sunday; therefore, the week count this script returns is one week off and therefore all sprint dates are skewed by one week. This may just be as simple as rebasing PR #22.