Update mypyc/codegen/emitmodule.py

Co-authored-by: Alex Waygood <[email protected]>

mypyc/codegen/emitmodule.py

@@ -993,7 +993,7 @@ def _toposort_visit(name: str) -> None:
             result.append(decl.declaration)
             decl.mark = True
 
-        for name in marked_declarations.keys():
+        for name in marked_declarations:
             _toposort_visit(name)
 
         return result