Is there documentation of all of the valid runtime values for .vc-config.json?

[btakita]

Description

I'm using @astrojs/vercel with bunjs. @astrojs/vercel generates a .vc-config.json with:

{
	"runtime": "nodejs18.x",
	"handler": "app/briantakita.me/dist/entry.mjs",
	"launcherType": "Nodejs",
	"supportsResponseStreaming": true
}

However, in a bun environment with a monorepo + git submodules, I get the build error:

Error: The following Serverless Functions contain an invalid "runtime":
  - render (nodejs18.x). Learn More: https://vercel.com/guides/serverless-function-contains-invalid-runtime-error

Is there a specific value for runtime: specifyi