Deploy specification GitHub action is broken

[nebasuke]

The deploy specification GitHub action, see https://github.com/ethereum/execution-apis/actions/workflows/deploy.yaml, has been broken for a while. This means that the recent changes, e.g. totalDifficulty now being optional, is not yet visible on https://ethereum.github.io/execution-apis/api-documentation/.

[fjl]

It's likely related to this issue: open-rpc/generator#721

The site is supposed to be created by 'gatsby'. The configuration for gatsby, including its package.json file, is created by the OpenRPC generator. The generator is not maintained anymore.