[llvm] workflows/new-issues: Use an llvmbot token to add labels (PR #120840)

[Tom Stellard via llvm-commits]

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@@ -15,7 +15,7 @@ jobs:
     steps:
       - uses: llvm/actions/issue-labeler at main
         with:
-          repo-token: ${{ secrets.GITHUB_TOKEN }}
+          repo-token: ${{ secrets.ISSUE_SUBSCRIBER_TOKEN }}
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tstellar wrote:

We use this token in the new-prs.yml workflow for the same purpose.  

https://github.com/llvm/llvm-project/pull/120840