build(deps): bump libz-sys from 1.1.16 to 1.1.20

Bumps [libz-sys](https://github.com/rust-lang/libz-sys) from 1.1.16 to 1.1.20.
- [Release notes](https://github.com/rust-lang/libz-sys/releases)
- [Commits](rust-lang/libz-sys@1.1.16...1.1.20)

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

Signed-off-by: dependabot[bot] <[email protected]>