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/[email protected]@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] <[email protected]>

Author: dependabot[bot]

Cargo.lock

@@ -22,5 +22,5 @@ thiserror = ">=1, <3"
 regex = "1.10"
 lazy_static = "1.5"
 derive-new = ">=0.6, <0.8"
-petgraph = { version = ">=0.5, <0.7", optional = true }
+petgraph = { version = ">=0.5, <0.9", optional = true }
 strum_macros = ">=0.20, <0.27"