Update fs4 requirement from 0.7 to 0.8 (#72)

Updates the requirements on [fs4](https://github.com/al8n/fs4-rs) to permit the latest version.
- [Release notes](https://github.com/al8n/fs4-rs/releases)
- [Commits](https://github.com/al8n/fs4-rs/commits)

---
updated-dependencies:
- dependency-name: fs4
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Cargo.toml

@@ -19,7 +19,7 @@ log = "0.4"
 memmap2 = "0.9.0"
 rand = "0.8.5"
 rand_distr = "0.4.3"
-fs4 = "0.7"
+fs4 = "0.8"
 # fs4 depends on rustix, but pulling this dependency explicitly into the tree
 # to use direct functions on FreeBSD
 rustix = { version = "0", features = [ "fs" ]}