python313Packages.btest: add missing multiprocess

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

@@ -2,6 +2,7 @@
   lib,
   buildPythonPackage,
   fetchFromGitHub,
+  multiprocess,
   pythonOlder,
   setuptools,
 }:
@@ -22,6 +23,8 @@ buildPythonPackage rec {
 
   build-system = [ setuptools ];
 
+  dependencies = [ multiprocess ];
+
   # No tests available and no module to import
   doCheck = false;