## What changes were proposed in this pull request?
This PR proposes to use https://rversions.r-pkg.org/r-release-win instead of https://rversions.r-pkg.org/r-release to check R's version for Windows correctly.
We met a syncing problem with Windows release (see #15709) before. To cut this short, it was ...
- 3.3.2 release was released but not for Windows for few hours.
- `https://rversions.r-pkg.org/r-release` returns the latest as 3.3.2 and the download link for 3.3.1 becomes `windows/base/old` by our script
- 3.3.2 release for WIndows yet
- 3.3.1 is still not in `windows/base/old` but `windows/base` as the latest
- Failed to download with `windows/base/old` link and builds were broken
I believe this problem is not only what we met. Please see 01ce943929 and also this `r-release-win` API came out between 3.3.1 and 3.3.2 (assuming to deal with this issue), please see `https://github.com/metacran/rversions.app/issues/2`.
Using this API will prevent the problem although it looks quite rare assuming from the commit logs in https://github.com/metacran/rversions.app/commits/master. After 3.3.2, both `r-release-win` and `r-release` are being updated together.
## How was this patch tested?
AppVeyor tests.
Author: hyukjinkwon <gurwls223@gmail.com>
Closes#18859 from HyukjinKwon/use-reliable-link.
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