Update versions of opus and mpg123 libraries

[bemoody]

This pull request updates the version numbers for the built-in libraries (for MacOS and Linux builds) to their latest upstream versions:

• libopus 1.4 -> 1.5.2 (see https://www.opus-codec.org/downloads/)
• libmpg123 1.32.3 -> 1.32.6 (see https://www.mpg123.org/download.shtml)

The other version numbers in linux_build.sh and mac_build.sh appear to be up-to-date (however, the current MacOS arm64 binary is out of date.)

I haven't done any testing beyond checking that it compiles on Debian 12 amd64, and running the soundfile test suite.

[bastibe]

Something about their build systems must have changed. The build scripts did not work at all.

[bemoody]

Could you paste the error message please?

[bemoody]

Hmm, okay, I see a few problems...

• Your github workflow is using the docker container "centos:7", which is dead as a doornail. If you want to continue building "manylinux_2_17" binaries then one possibility would be to use the "quay.io/pypa/manylinux2014_x86_64" container (https://github.com/pypa/manylinux).

• I don't think anyone would blame you for dropping CentOS 7 support at this point and moving to either Debian 10 (glibc 2.28) or Ubuntu 20.04 (glibc 2.31).

• linux_build.sh doesn't set -e, so it's easy for things to fail and be ignored.

• If you don't have pkg-config installed then libsndfile's configure will silently disable features. (It would be better to use --enable-external-libs --enable-mpeg.)

• The mpg123 sources have been reorganized, so you need -I$(pwd)/mpg123-$MPG123VERSION/src/include/ instead of -I$(pwd)/mpg123-$MPG123VERSION/src/libmpg123/.

[bastibe]

You're right. I think we can drop glibc 2.17 now that centos 7 is truly dead. If you'd like to help, I'd be grateful if you could commit the appropriate changes to build-libs.yml to #34.

Thank you, truly, for your help. I currently don't have a lot of time to work on this, so I'm very grateful for your help!