Three of the four features we asked for no longer hold. `compression-flate2` is now `compression-tar-gz`, and since we switch the defaults off we have to name `github` and `progress-bar` to keep the backend and the download bar. Four call sites moved with the API. `fetch` returns `Releases`, so `first` becomes `latest` and `version` is a method. `target_version_tag` is now `release_tag` and `identifier` is now `asset_identifier`; both take the same value and mean the same thing. Behaviour is unchanged. `asset_for` still matches on target and identifier in the same order, `bin_name` derives `bin_path_in_archive` by the same rule, and the target still defaults to the build triple. TLS stays on rustls, with no native-tls or openssl-sys pulled in, so the musl targets are unaffected. Add two ignored tests that need the network. One pins which asset the identifier resolves to for all six published targets, since every release ships a `.sha256` beside the archive and installing that over the binary would be silent and fatal. The other downloads a release into a temp path, installs it and runs it. Closes #438