Create scheduled workflow to create PR for language version updates

[Cyberbeni]

For languages that properly tag versions on github, using github.com/repoSlug/releases/latest redirect should be the best.
For example: https://github.com/apple/swift/releases/latest

Otherwise parsing the HTML of the download page seems to be the best option, for example the first <div class="toggleVisible" id="gox.y.z"> on https://golang.org/dl/ will give us the latest stable version.

[Cyberbeni]

Hm, even where the github releases are not properly done (rustup and go), the tags are still managed, so we could use this method to get the latest non-beta version tag: https://github.com/Cyberbeni/install-swift-tool/blob/master/src/installer.ts#L27-L38

(this.version would have to be '*', other parts of the code shouldn't require any explanation)

[Cyberbeni]

I guess the "go" part will have to be trimmed from the start of the tag

[rkm]

I can make a stab at this if no one else has started?

I noticed that dotnet already has a newer version, so we can use it as a test case.

[rkm]

Here's my initial working attempt. Which managed to produce this PR: rkm#4.

Any thoughts / feedback?