[libgpiod] libgpiod tests fail to build with Catch2 3.x

[Guillaume Gardet <Guillaume.Gardet@xxxxxxx>]

Hi,

libgpiod 1.6.3 only supports Catch2 2.x and fails to build against 3.x with the following error log:
[   70s] gpiod-cxx-test-main.cpp:9:10: fatal error: catch2/catch.hpp: No such file or directory
[   70s]     9 | #include <catch2/catch.hpp>
[   70s]       |          ^~~~~~~~~~~~~~~~~~
[   70s] compilation terminated.
[   70s] make[4]: *** [Makefile:494: gpiod-cxx-test-main.o] Error 1
[   70s] make[4]: *** Waiting for unfinished jobs....
[   70s] tests-chip.cpp:8:10: fatal error: catch2/catch.hpp: No such file or directory
[   70s]     8 | #include <catch2/catch.hpp>
[   70s]       |          ^~~~~~~~~~~~~~~~~~
[   70s] compilation terminated.

Catch2 did some breaking changes between 2.x and 3.x versions. See: https://github.com/catchorg/Catch2/blob/v3.0.1/docs/migrate-v2-to-v3.md#top

I have a patch for 1.6.x branch _only_ due to licensing issues on libgpiod 2.x. This patch make the switch from Catch2 2.x to 3.x but is not backward compatible, so once applied, you cannot build against Catch2 2.x anymore.
Are you interested in this patch?

Regards,
Guillaume