s/suffix/prefix/

CI custom build logic is hard to test

build.sbt

@@ -23,7 +23,7 @@ commands += Command.command("ci-windows") { s =>
 }
 
 def scalafixVersion: String = sys.env.get("TRAVIS_TAG") match {
-  case Some(v) if v.nonEmpty => v.stripSuffix("v")
+  case Some(v) if v.nonEmpty => v.stripPrefix("v")
   case _ => "0.6.0-M14"
 }