disable --allow-system-packages for generate-github-actions
disable --allow-system-packages for generate-github-actions

Summary: Fix github actions builds for projects depending on zstd

Reviewed By: wez

Differential Revision: D26743251

fbshipit-source-id: a3fd8a14750227d025bff763cca8aa683b26a422

facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift,facebook/fbthrift