[Qgis-psc] Enable Probot-Stale on qgis/QGIS

[Nyall Dawson]

On Wed, 27 Jun 2018 at 17:33, Matthias Kuhn <matthias at opengis.ch> wrote:
>
> Thanks everyone,
>
> it has been enabled for a test drive, let's see how it does :-)
>

...and just to prove that this is a fair system, a stale PR by
Matthias was the first to get pinged by probot!

https://github.com/qgis/QGIS/pull/7315#issuecomment-404074072

Nyall