Fix scripted scala3 test

Author: eed3si9n

build.sbt

@@ -27,6 +27,12 @@ lazy val root = (project in file("."))
         case _      => "2.0.0-M3"
       }
     }
+    scriptedSbt := {
+      scalaBinaryVersion.value match {
+        case "2.12" => "1.10.7"
+        case _      => "2.0.0-M3"
+      }
+    }
   })
 
 Global / onChangedBuildSource := ReloadOnSourceChanges

src/sbt-test/proguard/scala3/test.sbt

@@ -1,5 +1,5 @@
 import java.nio.file.{Files, FileSystems}
-import scala.jdk.CollectionConverters.*
+import collection.JavaConverters._
 import scala.sys.process.Process
 
 // for sbt scripted test: