Update bindgen requirement from 0.69.1 to 0.70.0 in /rust (#244)

Updates the requirements on [bindgen](https://github.com/rust-lang/rust-bindgen) to permit the latest version.
- [Release notes](https://github.com/rust-lang/rust-bindgen/releases)
- [Changelog](https://github.com/rust-lang/rust-bindgen/blob/main/CHANGELOG.md)
- [Commits](rust-lang/rust-bindgen@v0.69.1...v0.70.0)

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

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

rust/Cargo.toml

@@ -22,7 +22,7 @@ dirs = { version = "5.0", optional = true }
 download-bridgestan-src = ["dep:ureq", "dep:tar", "dep:flate2", "dep:dirs"]
 
 [build-dependencies]
-bindgen = "0.69.1"
+bindgen = "0.70.0"
 
 [dev-dependencies]
 approx = "0.5.1"