Update bindgen requirement from 0.66.0 to 0.68.1

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@v0.66.0...v0.68.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -16,5 +16,5 @@ generate-bindings = [ "bindgen"]
 update-bindings = [ "generate-bindings"]
 
 [build-dependencies]
-bindgen = { version = "0.66.0", optional = true }
+bindgen = { version = "0.68.1", optional = true }
 cc = "1.0.59"