Server(docs[docstring]): Add tmux_bin to Parameters section

why: tmux_bin parameter was missing from the Server class docstring,
violating the convention that all parameters are documented.
what:
- Add tmux_bin entry to Parameters section after socket_name_factory

Author: tony

src/libtmux/server.py

@@ -71,6 +71,7 @@ class Server(
     colors : str, optional
     on_init : callable, optional
     socket_name_factory : callable, optional
+    tmux_bin : str or pathlib.Path, optional
 
     Examples
     --------