extend stale bot to 90 days (#70)

Author: maryamhonari

.github/stale.yml

@@ -10,15 +10,15 @@ only: issues
 # Issue specific configuration
 issues:
   limitPerRun: 5
-  daysUntilStale: 28
-  daysUntilClose: 14
+  daysUntilStale: 90
+  daysUntilClose: 30
   markComment: >
     This issue has been automatically marked as stale because it has not had activity in the
-    last 28 days. It will be closed in the next 14 days if no further activity occurs.
+    last 90 days. It will be closed in the next 30 days if no further activity occurs.
     Thank you for your contributions.
   closeComment: >
     This issue has been automatically closed because it has not had activity in the
-    last 42 days. If this issue is still valid, please ping a maintainer.
+    last 120 days. If this issue is still valid, please ping a maintainer.
     Thank you for your contributions.
   exemptLabels:
     - request