change deprecated `serve_static_assets` to `serve_static_files` in staging
change deprecated `serve_static_assets` to `serve_static_files` in staging

dillia23/code-dot-org,pickettd/code-dot-org,dillia23/code-dot-org,rvarshney/code-dot-org,rvarshney/code-dot-org,pickettd/code-dot-org,rvarshney/code-dot-org,dillia23/code-dot-org,pickettd/code-dot-org,dillia23/code-dot-org,pickettd/code-dot-org,dillia23/code-dot-org,pickettd/code-dot-org,rvarshney/code-dot-org,pickettd/code-dot-org,pickettd/code-dot-org,dillia23/code-dot-org,dillia23/code-dot-org,rvarshney/code-dot-org,rvarshney/code-dot-org,pickettd/code-dot-org,rvarshney/code-dot-org,dillia23/code-dot-org,rvarshney/code-dot-org