use modern MiMa version

SethTisue · SethTisue · commit 530d9295375f · 2020-02-18T13:55:12.000-08:00
diff --git a/project/plugins.sbt b/project/plugins.sbt
@@ -1,4 +1,4 @@
 addSbtPlugin("org.scala-sbt" % "sbt-contraband" % "0.4.1")
-addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.3.0")
+addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "0.6.4")
 addSbtPlugin("de.heikoseeberger" % "sbt-header" % "5.4.0")
 addSbtPlugin("com.dwijnand" % "sbt-dynver" % "3.3.0")
