Update use-case.md

Author: BoxyUwU

.github/ISSUE_TEMPLATE/use-case.md

@@ -2,7 +2,7 @@
 name: Use case
 about: Describe your experiences using this feature
 title: '[Use Case]: '
-labels: A-generic-exprs C-use-case
+labels: A-generic-exprs, C-use-case
 assignees: ''
 
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