Reduce the number of days an issue is stale by 15
Reduce the number of days an issue is stale by 15

We're still within the 3 years and 2 months range. I opted to only
reduce this number by 15 instead of 25 because this change will mark
18 issues as stale rather than about 35.

We need to keep reducing this number, but we also don't want to flood
this process too much.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt