Buildkite SDK for Python

The `buildkite-sdk` is an open-source, multi-language Software Development Kit (SDK) that simplifies scripting the generation of pipeline steps for dynamic Buildkite pipelines in native languages like Python. It consumes the Buildkite pipeline schema to provide type-safe programmatic pipeline creation and serialization to YAML or JSON. The current version is 0.10.0 and it maintains a synchronized release cadence across all supported languages (Python, JavaScript/TypeScript, Go, Ruby, C#).