Laurent Rineau 2a8a32d6ad fix Prevent_deref<Union_find::iterator> ...

`std::iterator_traits` requires that the iterator type defines all five nested types.

I have also modified the implementation of

```c++
make_prevent_deref_range(Range)
```

2025-09-19 11:53:02 +02:00

..

Union_find.h

fix Prevent_deref<Union_find::iterator>

2025-09-19 11:53:02 +02:00