Update Rust crate petgraph to ^0.6.4

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
petgraph	dependencies	patch	^0.6.3 -> ^0.6.4

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Release Notes

petgraph/petgraph (petgraph)

### [`v0.6.4`](https://togithub.com/petgraph/petgraph/blob/HEAD/RELEASES.rst#Version-064-2023-08-21) [Compare Source](https://togithub.com/petgraph/petgraph/compare/petgraph@v0.6.3...petgraph@v0.6.4) \========================== - Update `indexmap` to 2.0.0 (`#568`\_) - Fix typos (`#544`\_) .. \_`#544`: [https://github.com/petgraph/petgraph/pull/544](https://togithub.com/petgraph/petgraph/pull/544) .. \_`#568`: [https://github.com/petgraph/petgraph/pull/568](https://togithub.com/petgraph/petgraph/pull/568)

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