Replace 'stale' Github action with the Probot Stale app

.gitattributes

@@ -4,4 +4,7 @@ LICENSE_windows.txt text eol=crlf
 libraries_used.txt text eol=lf
 libraries_used_windows.txt text eol=crlf
 gradlew.bat text eol=crlf
-gradlew text eol=lf
+gradlew text eol=lf
+
+# Tell GitHub’s linguist which files to ignore
+gradle/InnoSetup6/* linguist-vendored

.github/stale.yml

@@ -0,0 +1,19 @@
+# Number of days of inactivity before an issue becomes stale
+daysUntilStale: 25
+# Number of days of inactivity before a stale issue is closed
+daysUntilClose: 5
+# Issues with these labels will never be considered stale
+exemptLabels:
+  - enhancement
+# Set to true to ignore issues with an assignee
+exemptAssignees: true
+# Label to use when marking an issue as stale
+staleLabel: Stale
+# 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. If you
+  would like this to remain open, please comment,
+  otherwise this issue will be closed in 5 days.'
+# Comment to post when closing a stale issue. Set to `false` to disable
+closeComment: false