Apply suggestion from @tony

Co-authored-by: Tony Narlock <tony@git-pull.com>

Author: neubig

src/libtmux/neo.py

@@ -180,7 +180,7 @@ def _refresh(
 def get_output_format() -> tuple[list[str], str]:
     """Return field names and tmux format string for all Obj fields."""
     # Exclude 'server' - it's a Python object, not a tmux format variable
-    formats = [f for f in Obj.__dataclass_fields__.keys() if f != "server"]
+    formats = [f for f in Obj.__dataclass_fields__ if f != "server"]
     tmux_formats = [f"#{{{f}}}{FORMAT_SEPARATOR}" for f in formats]
     return formats, "".join(tmux_formats)