Extends "weekly downloads" period by at least one week

[TheTomasJ]

In the package detail, there is "weekly downloads" graph. I like to see how some package has evolved in the last year. But due to holidays and some other HR patterns, there are stronger and weaker weeks in the year and we cannot see the "one-year" change. E.g. now it is the 47. week of year 2024. But I can compare it only to 48 . week of year 2023, because week 47 is out of the range. Week 48/23 is very close to the desired week 47/23, but what if the week 48/23 was influeced by some public holidays. This is most relevant when the date is close to Christmas but there are same patterns through the year.

Proposal: extends the graph by at least one week.