fix: incorrect path for followers and followees

[ssiyad]

async fn followers() -> Vec<Follower> {
    let octo = octocrab::instance();
    octo.users(USER)
        .followers()
        .send()
        .await
        .unwrap()
        .into_stream(&octo)
        .try_collect::<Vec<Follower>>()
        .await
        .unwrap()
}

This results in a 404 error because the path being called is /users/users/<username>/followers. This PR removes the extra /users part. Same for following.