Refresh openapi.json from upstream

Only `info.description` changed ("Last updated: April 23, 2026" →
"April 30, 2026"); the field is OpenAPI metadata that does not surface
in any generated Python, so re-running the regen pipeline produces no
changes under `ionq_core/`. The upstream-sorted diff matches the
preview posted on this PR.

Resolves #38.

Author: splch