Create a "latest build" release for tagged release versions

[elcritch]

Currently there are releases such as Latest successful build for branch version-2-2 for the last successful build for that branch.

However there isn't anything similar for the tagged Nim releases. Take the latest Nim version v2.2.0 which is at Commit 78983f1. There's no nightlies release for "Latest build for release v2.2.0".

Ideally this would allow us to setup github runner actions which installed Nim simply by:

curl https://github.com/nim-lang/nightlies/releases/tag/latest-release-2.2.0/linux_arm64.tar.xz
untar linux_arm64.tar.xz

Specifically it'd need to be easy to do this:

NIM_VERSION=v2.2.0
curl https://github.com/nim-lang/nightlies/releases/tag/latest-release-${NIM_VERSION}/linux_arm64.tar.xz

[elcritch]

It appears the build scripts for nightlies have all the info needed, between here:

https://github.com/nim-lang/nightlies/blob/f8ae93238d532e694486a4dc88726e4b82830799/.github/workflows/nightlies.yml#L124C1-L125C1

And here:

nightlies/.github/workflows/nightlies.yml

Line 492 in f8ae932

tag='latest-${{ matrix.setting.branch }}'

[elcritch]

I'd make a PR but I don't understand the build action well and it's pretty massive bit of logic. :)