There have been some very weird issues, where
cargo keeps fetching older commits of glib-rs
and breaking the build like so [1]

Might be stale cache, or some http/git mirroring
shenanigans, so lets stop trying to use the
cache for now and check if the issue persists.

[1]: https://gitlab.freedesktop.org/slomo/gst-plugins-rs/-/jobs/4715922

We depend on 1.18.0 now instead of 1.17.2

We are caching the CARGO_HOME which includes git repos of
the gtk-rs bindings. Since we don't specify a branch
so it uses the default branch for the ref.

cargo build usually does an update if it has network access,
but its not guaranteed or the case for other tools like clippy
which may still point to the stale git snapshot like here:

https://gitlab.freedesktop.org/thaytan/gstreamer-rs/-/jobs/4165449

It's 2020.

This should be approximately the same as 1.17.90.

To keep it in sync with the bindings on top.

See https://freedesktop.pages.freedesktop.org/ci-templates/ci-fairy.html#checking-commits

In this setup it will check for any leftover fixup!/squash! commits and
that messages don't have the 'Signed-off-by:' tag.

They are endianness and version dependent.