ocamlPackages.bls12-381: migrate to finalAttrs

pkgs/development/ocaml-modules/bls12-381/gen.nix

@@ -6,14 +6,14 @@
   zarith,
 }:
 
-buildDunePackage rec {
+buildDunePackage (finalAttrs: {
   pname = "bls12-381-gen";
   version = "0.4.4";
 
   src = fetchFromGitLab {
     owner = "dannywillems";
     repo = "ocaml-bls12-381";
-    rev = "${version}-legacy";
+    rev = "${finalAttrs.version}-legacy";
     sha256 = "qocIfQdv9rniOUykRulu2zWsqkzT0OrsGczgVKALRuk=";
   };
 
@@ -34,4 +34,4 @@ buildDunePackage rec {
     license = lib.licenses.mit;
     maintainers = [ lib.maintainers.ulrikstrid ];
   };
-}
+})