[libsrtp] libSRTP version 2.4.0 has been released

Major changes in this release are: - Remove EKT files, this was never completed and the draft has since changed. - Adds support for Mbedtls as a crypto backend. - Support apple silicon build. - Adds support for the Meson build system. This is an alternative to Cmake and auto tools. For more details and a complete list of changes please see the CHANGES file. The following links are available for downloading: https://github.com/cisco/libsrtp/archive/v2.4.0.tar.gz https://github.com/cisco/libsrtp/archive/v2.4.tar.gz https://github.com/cisco/libsrtp/archive/v2.tar.gz Thank you to everybody that has contributed. libSRTP team.