Don't mark issues added to the project as stale

Prevent stale bot from auto closing issues added to the project

.github/stale.yml

   - "📌 pinned"
 
 # Set to true to ignore issues in a project (defaults to false)
-exemptProjects: false
+exemptProjects: true
 
 # Set to true to ignore issues in a milestone (defaults to false)
 exemptMilestones: false