Update scala-native to 0.5 in mdocVariables task

Author: xuwei-k

build.sbt

@@ -277,7 +277,7 @@ lazy val docs = project
       val latestScalaJSVersion =
         getLatestVersion(s"org.scala-js:scalajs-library_2.13:").getOrElse(scalaJSVersion)
       val latestNativeVersion =
-        getLatestVersion(s"org.scala-native:nativelib_native0.4_3:").getOrElse(nativeVersion)
+        getLatestVersion(s"org.scala-native:nativelib_native0.5_3:").getOrElse(nativeVersion)
 
       Map(
         "START_YEAR" -> startYear,