`ScalaVersion` rejects Scala 2 nightlies

[SethTisue]

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I'm trying to build and test more of Scalafix in the Scala 2 community build, but I keep hitting this:

[scalafix-rules] [info]   java.lang.Exception: 2.13.16-bin-ce78754 not a valid Scala Version.
[scalafix-rules] [info]   at scalafix.internal.config.ScalaVersion$.from(ScalaVersion.scala:138)

could the check be relaxed to allow nightlies?

(doc on nightlies: https://docs.scala-lang.org/overviews/core/nightlies.html)

[SethTisue]

context is https://github.com/scala/community-build/pull/1723 fyi @xuwei-k