Add a gh workflow to automate more parts of the SDK release processs https://github.com/OpenHands/software-agent-sdk/pull/1405

@chilly-france-44439 i think there is an edge case where new changes to main can unintentionally get included in the pypi release (that weren't tested on the release branch) https://github.com/OpenHands/software-agent-sdk/pull/1405#discussion_r2624288249

no need to apologize! always good to double-check 🙂