Bump smallvec from 1.6.0 to 1.6.1 (#2239)

Bumps [smallvec](https://github.com/servo/rust-smallvec) from 1.6.0 to 1.6.1.
- [Release notes](https://github.com/servo/rust-smallvec/releases)
- [Commits](https://github.com/servo/rust-smallvec/compare/v1.6.0...v1.6.1)

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

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
10 jobs for master in 33 minutes and 10 seconds (queued for 3 seconds)