build(deps): update snafu requirement from ^0.6 to ^0.8

Updates the requirements on [snafu](https://github.com/shepmaster/snafu) to permit the latest version.
- [Changelog](https://github.com/shepmaster/snafu/blob/main/CHANGELOG.md)
- [Commits](shepmaster/snafu@0.6.0...0.8.4)

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

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -47,4 +47,4 @@ backtrace = "^0.3"
 bitflags = "^1"
 lazy_static = "^1"
 libc = "^0.2"
-snafu = { version = "^0.6", features = ["backtraces-impl-backtrace-crate"] }
+snafu = { version = "^0.8", features = ["backtraces-impl-backtrace-crate"] }