Update libdatachannel and cpp-httplib to v0.23.1

[mickel8]

This PR:

• fixes fetching the newest libdatachannel version on the CI. TL;DR submodules versions are locked in .git/index. Executing git submodule update --init --recursive does not sync submodules with their remotes. To do so, one has to use --remote option. It's also important that we don't want to use --remote for cpp-httplib (as there might be breaking changes) and for libdatachannel's submodules (for the same reason). After discussion on libdatachannel discord, this change has been removed in 57668e8. Instead, just update libdatachannel time to time
• updates cpp-httplib, and libdatachannel and its Dockerfile. libdatachannel update should also fix aiortc <-> libdatachannel interoperability. The problem was in incorrect DTLS certificate version, which was fixed in Fix X509 certificate version with OpenSSL paullouisageneau/libdatachannel#1406 and X509_VERSION_1 is not defined for OpenSSL<V3 paullouisageneau/libdatachannel#1411

[sipsorcery]

Looks like there's a yaml problem.

Error: The template is not valid. .github/workflows/datachannel_echo-test.yml (Line: 27, Col: 21): Unexpected value ''

[mickel8]

Hi @sipsorcery,

my changes are minimal right now. Could you try running the workflow once again?

The error seems to come from

          password: ${{ secrets.CR_PAT }}

Can it be that the secret value is incorrectly set in the repo?