latest libc doesn't build on 1.47

Looks like all our CI jobs are now failing with:

```
error: failed to parse manifest at `/home/runner/.cargo/registry/src/github.202132.xyz-1ecc6299db9ec823/libc-0.2.128/Cargo.toml`

Caused by:
  feature `resolver` is required

  this Cargo does not support nightly features, but if you
  switch to nightly channel you can add
  `cargo-features = ["resolver"]` to enable this feature
```