fix(muscript): carry over fork on ExprGroup optimization

muscript/src/main/java/io/gitlab/jfronny/muscript/ast/dynamic/ExprGroup.java

@@ -91,7 +91,8 @@ public class ExprGroup extends DynamicExpr {
                                 .flatMap(Expr::extractSideEffects)
                                 .map(Expr::optimize),
                         Stream.of(fin.optimize())
-                ).toList()
+                ).toList(),
+                fork
         ).asDynamicExpr();
     }