def process_env(self) -> dict[str, str]:
        """Get the process env var dict for the environment."""
        project = self.project
        this_path = self.get_paths()["scripts"]
        python_root = os.path.dirname(project.python.executable)
        new_path = os.pathsep.join([this_path, os.getenv("PATH", ""), python_root])
        return {"PATH": new_path, "PDM_PROJECT_ROOT": str(project.root)}
Get the process env var dict for the environment.
src/pdm/environments/base.py