Add renderPages arg to run puppeteer with no sandbox

[nickspoons]

On my linux host I can't run the default npm run prerender (npm run build && hyperstatic) because puppeteer hangs when running in a sandbox. A quick DDG for "--no-sandbox" shows many other systems where the sandbox causes problems.

This PR adds a --no-sandbox flag to renderPages.ts, which passes the flag on to puppeteer. I can then update my package.json to "prerender": "npm run build && hyperstatic --no-sandbox" and it runs.