Update pr-auto-update.yml

Signed-off-by: Matty Widdop <[email protected]>

Author: MattyTheHacker

.github/workflows/pr-auto-update.yml

@@ -12,7 +12,7 @@ jobs:
     steps:
       - uses: CSSUoB/[email protected]
         env:
-          GITHUB_TOKEN: '${{ secrets.PR_AUTO_UPDATE_TOKEN }}'
+          GITHUB_TOKEN: '${{ secrets.PR_UPDATE_TOKEN }}'
           PR_FILTER: 'labelled'
           PR_LABELS: 'sync'
           MERGE_CONFLICT_ACTION: 'label'