stale workflow: fix syntax

.github/workflows/stale.yml

@@ -14,23 +14,5 @@ jobs:
           close-issue-label: wontfix
           close-pr-label: wontfix
           days-before-close: -1
-          exempt-issue-labels:
+          exempt-issue-labels: 'pinned,security,Bug,Serious Bug,Minor bug,Black hole bug,Special case Bug,Upstream bug,Feature Request'
-            - pinned
+          exempt-pr-labels: 'pinned,security,Bug,Serious Bug,Minor bug,Black hole bug,Special case Bug,Upstream bug,Feature Request'
-            - security
-            - Bug
-            - Serious Bug
-            - Minor bug
-            - Black hole bug
-            - Special case Bug
-            - Upstream bug
-            - Feature Request
-          exempt-pr-labels:
-            - pinned
-            - security
-            - Bug
-            - Serious Bug
-            - Minor bug
-            - Black hole bug
-            - Special case Bug
-            - Upstream bug
-            - Feature Request