Update serde_yaml requirement from 0.7 to 0.8
Update serde_yaml requirement from 0.7 to 0.8

Updates the requirements on [serde_yaml](https://github.com/dtolnay/serde-yaml) to permit the latest version.
- [Release notes](https://github.com/dtolnay/serde-yaml/releases)
- [Commits](https://github.com/dtolnay/serde-yaml/commits/0.8.0)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
michiel/xflow-rust,gears-project/gears-core-rust,gears-project/gears-core-rust,michiel/xflow-rust,gears-project/gears-core-rust,michiel/xflow-rust