These are the package versions currently shipped by Fedora. This allows
using system packages by setting
export MESON_PACKAGE_CACHE_DIR=/usr/share/cargo/registry/
Of course, other distros may place it somewhere else.
Ubuntu matches versions on syn and unicode-ident but is a tiny bit off
on quote and proc-macro2. However, given how far I was able to bump the
versions with only a tiny meson tweak to syn, I think it should work
with the Ubuntu versions as well.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/26726>
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