It's currently possible to set the amount of time before a pull request will be automatically declined (pullrequest.auto.decline.settings.global.inactivityWeeks), however the max time is 12 weeks. This may not be long enough in some situations.

Desired Behavior: 

• Allow the pullrequest.auto.decline.settings.global.inactivityWeeks to have a max allowed time of 6 months or alternatively allow the max amount of time to be configurable by the Administrator.