Bumps [serde](https://github.com/serde-rs/serde) from 1.0.90 to 1.0.91. - [Release notes](https://github.com/serde-rs/serde/releases) - [Commits](https://github.com/serde-rs/serde/compare/v1.0.90...v1.0.91) Signed-off-by: dependabot[bot] <support@dependabot.com>