Update generate workflow to install deps

[maddawik]

I tested this previously, https://github.com/vulncheck-oss/sdk-python/actions/runs/16597232644/job/46946834809 before merging - but there were no updates in the OpenAPI spec to exercise the real path - so there's some cleanup to do (dependencies are not installed, so pytest fails in this case: https://github.com/vulncheck-oss/sdk-python/actions/runs/16684924837)

[maddawik]

This issue is resolved - the release action failed on the latest run: https://github.com/vulncheck-oss/sdk-python/actions/runs/16697361937/job/47263474481 simply because the project at v0.0.17 does not have openapi.json committed to the project (no specs to diff between) - this should Just Work next time.