build(deps): bump third_party/yaml-cpp from `f531f8a` to `a8ba6a8`
build(deps): bump third_party/yaml-cpp from `f531f8a` to `a8ba6a8`

Bumps [third_party/yaml-cpp](https://github.com/jbeder/yaml-cpp) from `f531f8a` to `a8ba6a8`.
- [Release notes](https://github.com/jbeder/yaml-cpp/releases)
- [Commits](https://github.com/jbeder/yaml-cpp/compare/f531f8a8c3f8ca0923f9219c72fcca511555f824...a8ba6a8dca0b9a7ca8fd56d804e45cf5a8270f87)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
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