You are recommended to use Websocat 1.9.0, not this release. This release does not necessarily preclude Websocat 1.10.0 in the future.
This release showcases rewritten Websocat using Tokio 1, Hyper 0.14 and Tungstenite instead of legacy dependencies. This opens up a world of QUIC, rfc8441 and other new things to keep Websocat relevant. A lot of features from Websocat1 are not yet implemented, CLI UI compatibility with Websocat1 is also not implemented yet. Help is partially implemented. Book is just started. Release artifacts build script is not dockerised.
It's "3.0" instead of "2.0" because of Websocat2 was supposed to be version based on Tokio 0.2 + Hyper 0.12 (or Hyper-less), split to multiple crates; but that was abandoned.
websocat3.i686-pc-windows-gnu, websocat3.x86_64-apple-darwin and websocat3.x86_64-pc-windows-gnu are built against native-tls, all the rest is built against rustls + webpki-roots.