No retry resolving the R version in setup-r (api.r-hub.io/rversions)

[nbenn]

The R version is resolved in determineVersion() with a single GET to api.r-hub.io/rversions/resolve/... via getJSON(), which is a bare fetch with no retry:

• actions/setup-r/src/installer.ts

  Lines 808 to 814 in 0d1fbb4

  	let os: string = OS != "linux" ? OS : await getLinuxPlatform();
  	let url: string =
  	"https://api.r-hub.io/rversions/resolve/" + version + "/" + os;
  	if (ARCH) {
  	url = url + "/" + ARCH;
  	}
  	var tags = await getJSON<IRVersion>(url);

• actions/setup-r/src/installer.ts

  Lines 772 to 778 in 0d1fbb4

  	async function getJSON<T>(url: string): Promise<T | undefined> {
  	const response = await fetch(url, {
  	headers: { "User-Agent": "setup-r" },
  	});
  	if (!response.ok) return undefined;
  	return (await response.json()) as T;
  	}

A transient timeout resolving the version therefore fails the job (Error: Request timeout: /rversions/resolve/release/linux-ubuntu-24.04/x86_64).

I realise retry has been raised and declined before (#189, #755); this is narrower — just that one resolve GET. Would a small retry-with-backoff (3–5 attempts) around it be worth considering? Happy to open a PR if so.

[gaborcsardi]

Sure, that seems like a good idea, a PR is welcome.