namada_sdk::rpc::get_all_validators always returns empty set

[dadamu]

namada_sdk::rpc::get_all_validators always returns empty set whenever epoch is set to a valid epoch number like 1 or 2.

let validators = namada_sdk::rpc::get_all_validators(&client, Epoch::from(1)).await?;
println!("{:?}", validators); // {}

[sug0]

this is not a bug, it's intentional behavior. we prune validator sets after a certain number of epochs

#1944