Try to build on 3.3.4 (#635)

If this works, it gives uPickle and Ammonite a path to supporting Scala
3.3.x again

Author: lihaoyi

build.sc

@@ -17,8 +17,8 @@ import com.github.lolgab.mill.mima._
 val scala212  = "2.12.18"
 val scala213  = "2.13.11"
 
-val scala3   = "3.4.2"
-val scalaNative = "0.5.0"
+val scala3   = "3.3.4"
+val scalaNative = "0.5.5"
 val acyclic = "0.3.12"
 
 val sourcecode = "0.4.2"