feat: bump downloaded go to version 1.23.4

If Sage is invoked in an environment where Go is not available in `$PATH`,
Sage will download it.

This should not affect any users that has Go installed outside of an
Sage repo.

sg/makefile.go

@@ -15,7 +15,7 @@ import (
 	"go.einride.tech/sage/internal/strcase"
 )
 
-const defaultGoVersion = "1.20.2"
+const defaultGoVersion = "1.23.4"
 
 type Makefile struct {
 	Namespace     interface{}