Bump petgraph from 0.6.2 to 0.6.3 (#105)

Bumps [petgraph](https://github.com/petgraph/petgraph) from 0.6.2 to 0.6.3.
- [Release notes](https://github.com/petgraph/petgraph/releases)
- [Changelog](https://github.com/petgraph/petgraph/blob/master/RELEASES.rst)
- [Commits](https://github.com/petgraph/petgraph/commits/0.6.3)

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

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

Author: dependabot[bot]

Cargo.lock

@@ -19,7 +19,7 @@ thiserror = "1.0"
 lazy_static = "1.4.0"
 
 [dependencies.petgraph]
-version = "0.6.2"
+version = "0.6.3"
 features =  [ "serde-1" ]
 
 [dependencies.chrono]