Unit 1.31.0 released

[Timo Stark]

Hi, NGINX Unit community,

We are delighted to announce Unit 1.31.0, which marks a significant milestone
following the release of 1.30 in May. Over the past 15 weeks, our dedicated
team has been hard at work developing an innovative language module for NGINX
Unit. We are excited to introduce the Unit WebAssembly (WASM) feature as part
of this release, which represents a significant leap forward in Unit's
capabilities.

This is a technology preview of WebAssembly support in Unit, and we look
forward to learning more about the use cases and ideas that the community will
share with us.

This release also brings a notable addition to our repertoire - the ability to
send response headers and harness the power of response header variables within
the configuration. These enhancements will greatly increase the flexibility and
customization options available to you.

Complementing these key advancements, we have carefully addressed a spectrum of
minor bug fixes and introduced additional refinements to ensure a seamlessly
enhanced user experience.

*) Python support for ASGI lifespan_state (external contributor: synodriver)

*) the unitc CLI tool now provides interactive editing of configuration URIs

To learn more, see our blog post about this release:
http://unit.nginx.org/news/2023/unit-1.31.0-released/

Changes with Unit 1.31.0                                         31 Aug 2023

    *) Change: if building with njs, version 0.8.0 or later is now required.

    *) Feature: technology preview of WebAssembly application module.

    *) Feature: "response_headers" option to manage headers in the action
       and fallback.

    *) Feature: HTTP response header variables.

    *) Feature: ASGI lifespan state support. Thanks to synodriver.

    *) Bugfix: ensure that $uri variable is not cached.

    *) Bugfix: deprecated options were unavailable.

    *) Bugfix: ASGI applications inaccessible over IPv6.

Wbr, Timo & the Unit team