Determine latest release by date in site plugin

[armanbilge]

I'm looking at this part:

sbt-typelevel/site/src/main/scala/org/typelevel/sbt/TypelevelSitePlugin.scala

Lines 252 to 258 in 7aed1b8

	private lazy val currentRelease = Def.setting {
	// some tricky logic here ...
	// if the latest release is a pre-release (e.g., M or RC)
	// and there are no stable releases it is bincompatible with,
	// then for all effective purposes it is the current release
	val release = GitHelper.previousReleases(fromHead = true, strict = false) match {

The current strategy has created problems for http4s 0.22 in http4s/http4s#6402.