Update build.mill

Author: lihaoyi

build.mill

@@ -8,7 +8,7 @@ import scalalib._
 import scalanativelib._
 import mill.scalalib.publish.{Developer, License, PomSettings, VersionControl}
 
-import mill.main.VcsVersion
+import mill.vcs.VcsVersion
 import com.github.lolgab.mill.mima._
 
 val scalaNextVersion = sys.props.get("scalaNextVersion")