Update bindgen requirement from 0.69 to 0.70

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@v0.69.0...v0.70.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

ttf2mesh-sys/Cargo.toml

@@ -8,5 +8,5 @@ license = "MIT"
 readme = "README.md"
 
 [build-dependencies]
-bindgen = "0.69"
+bindgen = "0.70"
 cc = "1.0"