chore(Server.attached_sessions): Use .filter()

Author: tony

src/libtmux/server.py

@@ -260,7 +260,7 @@ def attached_sessions(self) -> t.List[Session]:
         -------
         list of :class:`Session`
         """
-        return [s for s in self.sessions if s.session_attached != "0"]
+        return self.sessions.filter(session_attached__noeq="1")
 
     def has_session(self, target_session: str, exact: bool = True) -> bool:
         """Return True if session exists.