pass down extensions env var to validation step

Author: filiptronicek

.github/workflows/validate-pr.yml

@@ -35,6 +35,7 @@ jobs:
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           REPOSITORY: ${{ github.repository }}
+          EXTENSIONS: ${{ env.EXTENSIONS }}
         with:
           script: |
             const script = require('./scripts/publish-extensions.js');