add github token

Author: mbektas

.github/workflows/prerelease.yml

@@ -35,6 +35,7 @@ jobs:
         uses: softprops/action-gh-release@v1
         if: steps.release-exists.outputs.result == 'false'
         with:
+          token: ${{ secrets.JLAB_APP_TOKEN }}
           body: '## JupyterLab Desktop v${{ steps.package-info.outputs.version}}'
           draft: true
           prerelease: true