use scalafmtCheckAll

[xuwei-k]

test:scalafmtCheck syntax is deprecated

[warn] sbt 0.13 shell syntax is deprecated; use slash syntax instead: Test / scalafmtCheck

https://github.com/scalameta/sbt-scalafmt/blob/3cc5809c6c6ece5bf85445c96a80f2cb6a60c890/plugin/src/main/scala/org/scalafmt/sbt/ScalafmtPlugin.scala#L60-L63

    val scalafmtAll = taskKey[Unit](
       "Execute the scalafmt task for all configurations in which it is enabled. " +
        "(By default this means the Compile and Test configurations.)"

[tsuyoshizawa]

Thanks!