Bump libz-sys from 1.1.16 to 1.1.18

Bumps [libz-sys](https://github.com/rust-lang/libz-sys) from 1.1.16 to 1.1.18.
- [Release notes](https://github.com/rust-lang/libz-sys/releases)
- [Commits](rust-lang/libz-sys@1.1.16...1.1.18)

---
updated-dependencies:
- dependency-name: libz-sys
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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