v0.15.0 - roles, improved secret handling

• added #37 implementing roles management (@semtisem)
• breaking change: endpoints can no longer be called as attributes and need to be called as method

// this is now invalid
client.users.get_users(...).await?;
// this is now mandatory
client.users().get_users(...).await?;

• breaking change: separated auth / client mods and re-exported models - this is in preparation to make the dco3::client mod private

// auth related models are still in dco3::auth
use dco3::auth::{OAuth2Flow, Connected, Disconnected, Provsioning};
// error is re-exported on level higher
use dco3::errors::DracoonClientError;
// internal auth models are still found in dco3::auth::models
use dco3::auth::models::{DracoonErrorResponse, DracoonAuthErrorResponse};

• made secret access explicit and ensure secrets are zeroized on drop (added secrecy to dependencies and wrapped tokens, plain keypair and credentials)
• dependency updates

What's Changed

• feature/roles by @semtisem in #37
• feature/credentials by @unbekanntes-pferd in #38
• chore: bump bytes to 1.7 by @unbekanntes-pferd in #39

Full Changelog: v0.14.0...v0.15.0