Use a working version of nghttp2-asio

The latest upstream version does not build on Boost 1.87, and there's a
nasty crash in the destructor which led to a nice little heap of hair on
our desks. It's time to fork that thing.

Link: nghttp2/nghttp2-asio#9
Link: nghttp2/nghttp2-asio#25
Change-Id: Iec9619ce45e7e76f0781d39966d0b6c7cc6fa778

Author: jktjkt

.zuul.yaml

@@ -6,7 +6,7 @@
     required-projects: &projects
       - CzechLight/dependencies
       - name: github/nghttp2/nghttp2-asio
-        override-checkout: main
+        override-checkout: cesnet/main
     vars:
       zuul_work_dir: "{{ zuul.projects[zuul.project.canonical_hostname + '/CzechLight/rousette'].src_dir }}"
 

README.md

@@ -84,7 +84,8 @@ In practical terms, this means that the NACM access rules for the following XPat
 
 ## Dependencies
 
-- [nghttp2-asio](https://github.com/nghttp2/nghttp2-asio) - asynchronous C++ library for HTTP/2
+- [nghttp2-asio](https://github.com/CESNET/nghttp2-asio) - asynchronous C++ library for HTTP/2
+  - we strongly recommend using [our fork](https://github.com/CESNET/nghttp2-asio) which appears to be better maintained, and which contains important bugfixes which have not been merged upstream yet
 - [sysrepo-cpp](https://github.com/sysrepo/sysrepo-cpp) - object-oriented bindings of the [*sysrepo*](https://github.com/sysrepo/sysrepo) library
 - [libyang-cpp](https://github.com/CESNET/libyang-cpp) - C++ bindings for *libyang*
 - [PAM](http://www.linux-pam.org/) - for authentication