Feature Request: Option to ignore weekends in calculation of number of stale days

[boopathi]

While calculating daysUntilStale, or daysUntilClose, when these numbers are configured to a low value, issues or prs that are created during one week gets closed over the following weekend when there are no updates during the weekends. Constantly going over PRs closed by stale bot on Mondays and reopening them is cumbersome.

Proposal: A new option to mark and avoid weekends in counting number of days until stale / close.

includeWeekends: false # defaults to true