Update acyclic to 0.3.15

Author: scala-steward

build.mill

@@ -20,7 +20,7 @@ val scala213  = "2.13.11"
 
 val scala3   = "3.3.4"
 val scalaNative = "0.5.5"
-val acyclic = "0.3.12"
+val acyclic = "0.3.15"
 
 val sourcecode = "0.4.2"