ocamlPackages.merlin-extend: migrate to finalAttrs

pkgs/development/ocaml-modules/merlin-extend/default.nix

@@ -5,12 +5,12 @@
   cppo,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "merlin-extend";
   version = "0.6.2";
 
   src = fetchurl {
-    url = "https://github.com/let-def/merlin-extend/releases/download/v${version}/merlin-extend-${version}.tbz";
+    url = "https://github.com/let-def/merlin-extend/releases/download/v${finalAttrs.version}/merlin-extend-${finalAttrs.version}.tbz";
     hash = "sha256-R1WOfzC2RGLyucgvt/eHEzrPoNUTJFK2rXhI4LD013k=";
   };
 
@@ -22,4 +22,4 @@ buildDunePackage rec {
     license = lib.licenses.mit;
     maintainers = [ ];
   };
-}
+})