fix: auto-assigner filename as per docs

Author: heitorlessa

.github/workflows/auto_assign_issues.yml renamed to .github/auto_assign-issues.yml

@@ -1,9 +1,8 @@
 addAssignees: true
 
-# The list of users to assign to new issues. 
+# The list of users to assign to new issues.
 # If empty or not provided, the repository owner is assigned
 assignees:
   - heitorlessa
   - nmoutschen
   - cakepietoast
-