python310Packages.bcrypt: add libiconv on darwin

pkgs/development/python-modules/bcrypt/default.nix

@@ -8,6 +8,8 @@
 , pythonOlder
 , cffi
 , pytestCheckHook
+, libiconv
+, stdenv
   # for passthru.tests
 , asyncssh
 , django_4
@@ -45,6 +47,9 @@ buildPythonPackage rec {
     rust.rustc
   ]);
 
+  # Remove when https://github.com/NixOS/nixpkgs/pull/190093 lands.
+  buildInputs = lib.optional stdenv.isDarwin libiconv;
+
   propagatedBuildInputs = [
     cffi
   ];