build(deps): bump petgraph from 0.6.5 to 0.8.1

Bumps [petgraph](https://github.com/petgraph/petgraph) from 0.6.5 to 0.8.1.
- [Release notes](https://github.com/petgraph/petgraph/releases)
- [Changelog](https://github.com/petgraph/petgraph/blob/master/CHANGELOG.md)
- [Commits](https://github.com/petgraph/petgraph/compare/petgraph@v0.6.5...petgraph@v0.8.1)

---
updated-dependencies:
- dependency-name: petgraph
  dependency-version: 0.8.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

Cargo.lock

@@ -63,7 +63,7 @@ strum_macros = "0.26.4"
 slog-async = "2.5.0"
 slog-envlogger = "2.1.0"
 slog-term = "2.7.0"
-petgraph = "0.6.5"
+petgraph = "0.8.1"
 tiny-keccak = "1.5.0"
 tokio = { version = "1.38.0", features = [
     "time",