Add semantic versioning to hydra-api.yaml

[eureka-cpu]

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It would just be sort of nice to know when the api has changed and what changed between versions, etc. It would be easier to create actions that create libraries for languages, such as Rust, if the version changed when it's updated.

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Bump the api version according to semantic versioning

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I could maintain my own copy, but that would be a pain as I am not actively maintaining the api

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