Fix mypy type-check error

Signed-off-by: Donald Hunter <[email protected]>

Author: donaldh

sphinx/domains/c/_symbol.py

@@ -119,7 +119,7 @@ def __init__(
 
     @property
     def _children(self) -> Sequence[Symbol]:
-        return self._childrenByName.values()
+        return list(self._childrenByName.values())
 
     def _add_child(self, child: Symbol) -> None:
         name = child.ident.name