chore(deps): update actions/github-script action to v8

Author: renovate[bot]

.github/workflows/add-zenhub-label.yml

@@ -13,7 +13,7 @@ jobs:
     permissions:
       issues: write
     steps:
-      - uses: actions/github-script@v6
+      - uses: actions/github-script@v8
         with:
           script: |
             github.rest.issues.addLabels({