Bump smallvec from 0.6.9 to 0.6.10
Bumps [smallvec](https://github.com/servo/rust-smallvec) from 0.6.9 to 0.6.10.
- [Release notes](https://github.com/servo/rust-smallvec/releases)
- [Commits](https://github.com/servo/rust-smallvec/commits)
Signed-off-by: dependabot-preview[bot] <support@dependabot.com>