Update sphinx/writers/texinfo.py

Co-authored-by: Takeshi KOMIYA <i.tkomiya@gmail.com>

Author: danieleades

sphinx/writers/texinfo.py

@@ -320,7 +320,7 @@ def collect_rellinks(self) -> None:
         """Collect the relative links (next, previous, up) for each "node"."""
         rellinks = self.rellinks
         node_menus = self.node_menus
-        for id in node_menus.keys():
+        for id in node_menus:
             rellinks[id] = ['', '', '']
         # up's
         for id, entries in node_menus.items():