Hugo 123.0 and later renders to disk by default

[maelle]

Per https://discourse.gohugo.io/t/upgrading-to-go1-22-1-hugo-0-124-1-causes-multiple-errors/49013/8

With v0.123.0 and later, Hugo’s development server renders to disk in the public directory.

https://gohugo.io/commands/hugo_server/

So depending on the Hugo version, the current logic for the render_to_disk argument of hugo_start() is wrong.