[Security] Bump smallvec from 0.6.9 to 0.6.14

Bumps [smallvec](https://github.com/servo/rust-smallvec) from 0.6.9 to 0.6.14. **This update includes security fixes.**
- [Release notes](https://github.com/servo/rust-smallvec/releases)
- [Commits](servo/rust-smallvec@v0.6.9...v0.6.14)

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