build(deps): update petgraph requirement to include 0.7 (#1226)

Updates the requirements on [petgraph](https://github.com/petgraph/petgraph) to permit the latest version.
- [Changelog](https://github.com/petgraph/petgraph/blob/master/RELEASES.rst)
- [Commits](https://github.com/petgraph/petgraph/compare/[email protected]@v0.7.0)

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

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

prost-build/Cargo.toml

@@ -19,7 +19,7 @@ heck = { version = ">=0.4, <=0.5" }
 itertools = { version = ">=0.10, <=0.14", default-features = false, features = ["use_alloc"] }
 log = "0.4.4"
 multimap = { version = ">=0.8, <=0.10", default-features = false }
-petgraph = { version = "0.6", default-features = false }
+petgraph = { version = ">=0.6, <=0.7", default-features = false }
 prost = { version = "0.13.4", path = "../prost", default-features = false }
 prost-types = { version = "0.13.4", path = "../prost-types", default-features = false }
 tempfile = "3"