Add 'write' role to vouch manage action (#18718)

.github/workflows/vouch-manage-by-issue.yml

@@ -33,6 +33,6 @@ jobs:
         with:
           issue-id: ${{ github.event.issue.number }}
           comment-id: ${{ github.event.comment.id }}
-          roles: admin,maintain
+          roles: admin,maintain,write
         env:
           GITHUB_TOKEN: ${{ steps.committer.outputs.token }}