Update snafu requirement from 0.7 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@0.7.0...0.8.0)

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

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

Cargo.toml

@@ -11,7 +11,7 @@ readme="README.md"
 [dependencies]
 url = "2.1.1"
 log = "0.4.8"
-snafu = "0.7"
+snafu = "0.8"
 
 [dev-dependencies]
 doc-comment = "0.3.3"