build: lutin is actually not mandatory to use sasa

sasa.opam

@@ -26,9 +26,11 @@ depends: [
   "functory"
   "rdbg" { >= "1.200" }
   "lustre-v6"
+]
+depopts: [
+  "ledit"
   "lutin"
 ]
-# depopts: [ "ledit" ]
 build: [make "build"]
 install: ["dune" "install"]
 post-messages: ["The last version can be obtained via (opam repo add) http://www-verimag.imag.fr/DIST-TOOLS/SYNCHRONE/opam-repository/ "]