rust: run `cargo clippy`
These automatic fixes are good to have because they make the code
more idiomatic and less surprising.
The transform from `sort` -> `sort_unstable` is questionable, but this is
only in a test, so it doesn't matter in our case.
graft c-ext
graft debian
graft zstd
graft tests
include make_cffi.py
include setup_zstd.py
include zstd.c
include LICENSE
include NEWS.rst