chore(probot-stale): add probot-stale configuration (#2640)

.github/stale.yml

@@ -0,0 +1,28 @@
+# Configuration for probot-stale - https://github.com/probot/stale
+
+# Number of days of inactivity before an Issue or Pull Request becomes stale
+daysUntilStale: 60
+# Number of days of inactivity before a stale Issue or Pull Request is closed
+daysUntilClose: 7
+# Issues or Pull Requests with these labels will never be considered stale. Set to `[]` to disable
+exemptLabels:
+  - bug
+  - discussion
+  - need-verify
+  - pending-reply
+# Label to use when marking as stale
+staleLabel:
+  - wontfix
+  - duplicate
+  - invalid
+# Comment to post when marking as stale. Set to `false` to disable
+markComment: >
+  This issue has been automatically marked as stale because lack of
+  recent activity. It will be closed if no further activity occurs. Thank you
+  for your contributions.
+# Comment to post when removing the stale label. Set to `false` to disable
+unmarkComment: false
+# Comment to post when closing a stale Issue or Pull Request. Set to `false` to disable
+closeComment: false
+# Limit to only `issues` or `pulls`
+# only: issues