TODO: fix zsync2 build issues with gcc-15-based images

[bastimeyer]

The manylinux images have received an update with GCC 15, which breaks the zsync2 build:
pypa/manylinux@1727273

docker build -t streamlink-appimage-container-x86_64:latest --build-arg PYTHON_VERSION=3.14 --build-arg BASEIMAGE=quay.io/pypa/manylinux_2_28_x86_64@sha256:c25f78ecbe6435a2c3867f9def9d36ea18f6f9bbe2baddde51c0f13d64d4f7d2 .

The issue appears to be caused by the dependencies which zsync2 pulls itself, namely args 6.4.6 and cpr 1.8.3 (which itself pulls libcurl 7.80.0):

• https://github.com/AppImageCommunity/zsync2/blob/f855a8b4d7c2533b62e0c967da59e21bffd44ac3/lib/CMakeLists.txt#L11-L87
• https://github.com/libcpr/cpr/blob/1.8.3/CMakeLists.txt#L246-L249
• https://github.com/Taywee/args
• https://github.com/libcpr/cpr

There are lots of issues with this cpr version.

The versions pinpointed by zsync2 are rather old. I've already tried building newer versions explicitly, but my attempts failed so far.

---

The GCC-15 update was immediately reverted again due to other/unrelated issues, but it's unclear if the next attempt will work. For now, the builds work fine again:
pypa/manylinux@7406547

docker build --no-cache -t streamlink-appimage-container-x86_64:latest --build-arg PYTHON_VERSION=3.14 --build-arg BASEIMAGE=quay.io/pypa/manylinux_2_28_x86_64@sha256:27aa6e8707aec397cc7e9850343b2703879a92b3dc818c93e07726ff1231c11d .

---

Ref
https://quay.io/repository/pypa/manylinux_2_28_x86_64?tab=tags