Stop using "builds", switch to using "functions"

[simonw]

https://vercel.com/docs/configuration#project/builds suggests that "builds" will eventually be deprecated. We use that here:

datasette-publish-vercel/datasette_publish_vercel/__init__.py

Line 204 in 2a4723e

"builds": [{"src": "index.py", "use": "@now/python"}],

[simonw]

It looks like functions have to run out of an api directory - https://vercel.com/docs/configuration#project/functions

But then the "rewrites" mechanism can hopefully be used to say "all traffic to /* should be handed off to this function". https://vercel.com/docs/configuration#project/rewrites

{
  "rewrites": [
    { "source": "/about", "destination": "/about-our-company.html" },
    { "source": "/resize/:width/:height", "destination": "/api/sharp" },
    { "source": "/user/:id", "destination": "/api/user" },
    { "source": "/proxy/:match*", "destination": "https://example.com/:match*" }
  ]
}

So presumably we would need something like this:

{
  "rewrites": [
    { "source": "/:path*", "destination": "/api/datasette.py/:match*" },
  ]
}

[simonw]

This may be why I've not been able to test the Vercel fix for the percent encoding issue in #28 - vercel/vercel#5575 (comment)