v4.0.0

What's Changed

• Provide into_ssl() for ConnectConfiguration by @eaufavor in #152
• Enable P-521 with "kx-safe-default" by @cjpatton in #166
• Add new(), connect(), accept() and handshake() to SslStream by @eaufavor in #153
• deps: update to bindgen 0.68 by @poliorcetics in #167
• Introduce async callbacks by @nox in #134
• Remove boring::fips::enable (fixes #150) by @nox in #169
• Expose SHA-512/256 by @sabjank in #103
• Improve X509VerifyResult by @nox in #171
• Introduce a new set of env variables specific to FIPS builds by @nox in #170
• Rework rpk and no-patches features by @nox in #172
• Introduce set_async_get_session_callback by @nox in #174
• Improve cross-building support, with some CI builds for macOS by @nox in #176
• hyper and tokio "full" feature for dev builds only by @shahn in #180
• Remove Sync trait bounds on callback futures by @nox in #183

Full Changelog: v3.1.0...v4.0.0