Bump savvy-bindgen from 0.6.7 to 0.6.8 in /src/rust

Bumps [savvy-bindgen](https://github.com/yutannihilation/savvy) from 0.6.7 to 0.6.8.
- [Release notes](https://github.com/yutannihilation/savvy/releases)
- [Changelog](https://github.com/yutannihilation/savvy/blob/main/CHANGELOG.md)
- [Commits](yutannihilation/savvy@v0.6.7...v0.6.8)

---
updated-dependencies:
- dependency-name: savvy-bindgen
  dependency-type: indirect
  update-type: version-update:semver-patch
...

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