Fixed typo in property name.

Author: hategan

src/psij/job_spec.py

@@ -137,7 +137,7 @@ def __init__(self, executable: Optional[str] = None, arguments: Optional[List[st
         # care of the conversion, but mypy gets confused
         self._directory = _to_path(directory)
         self.inherit_environment = inherit_environment
-        self.environment = _to_env_dict(environment)
+        self._environment = _to_env_dict(environment)
         self._stdin_path = _to_path(stdin_path)
         self._stdout_path = _to_path(stdout_path)
         self._stderr_path = _to_path(stderr_path)