Randomized iteration order for `PyGraph.neighbors`

[adamglos92]

Information

• rustworkx version: 0.17.1
• Python version: 3.12.11
• Rust version: (I believe it is not installed as I'm only using python version)
• Operating system: Linux aarch64 (devcontainer in macOS arm64)

What is the current behavior?

For a fixed graph I'm getting neighbors in random order.

What is the expected behavior?

Arbitrary, but fixed order

Judging on implementation, set is the problem (but I'm no Rust expert)

    pub fn neighbors(&self, node: usize) -> NodeIndices {
        NodeIndices {
            nodes: self
                .graph
                .neighbors(NodeIndex::new(node))
                .map(|node| node.index())
                .collect::<HashSet<usize>>()
                .drain()
                .collect(),
        }
    }

Steps to reproduce the problem

import rustworkx.generators as gen

for _ in range(3):
    g = gen.path_graph(5)
    print(g.neighbors(2))