Tame down stale bot (#344)

- Bump from 30 to 90 days
- Add "confirmed" label to keep issue from being marked stale
- Prevent issues being marked stale if they're in projects, milestones,
  or are assigned

.github/stale.yml

@@ -1,13 +1,22 @@
 # Number of days of inactivity before an issue becomes stale
-daysUntilStale: 30
+daysUntilStale: 90
 # Number of days of inactivity before a stale issue is closed
 daysUntilClose: 14
+
 # Label
 staleLabel: 'stale'
+exemptLabels:
+  - confirmed
+
+# Don't mark issues in projects, milestones, or that are assigned as stale
+exemptProjects: true
+exemptMilestones: true
+exemptAssignees: true
+
 # Comment to post when marking an issue as stale. Set to `false` to disable
 markComment: >
   This issue has been automatically marked as stale because it has not had
   recent activity. It will be closed if no further activity occurs. Thank you
   for your contributions.
 # Comment to post when closing a stale issue. Set to `false` to disable
-closeComment: false
+closeComment: false