chore(workflows): add stale workflow (#299)

camunda/team-automation-platform#147

.github/workflows/close-stale-issues.yml

@@ -0,0 +1,14 @@
+# This workflow warns and then closes issues and PRs that have had no activity for a specified amount of time.
+#
+# You can adjust the behavior by modifying this file.
+# For more information, see:
+# https://github.com/actions/stale
+name: 'Close stale issues and PRs'
+on:
+  schedule:
+    - cron: '0 2 * * 2-6'
+  workflow_dispatch: # can be used to trigger the workflow manually
+
+jobs:
+  call-reusable-flow:
+    uses: camunda/automation-platform-github-actions/.github/workflows/close-stale-issues.yml@main