Upsert regional prices

{  "priceId": "price_1a2b3c4d",  "overrides": [    {      "currency": "eur",      "price": 1800    }  ],  "object": "plan_regional_pricing",  "livemode": false}

{  "error": {    "type": "validation_error",    "code": "validation_error",    "message": "The request contains an invalid parameter.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/validation_error.md"  }}

{  "error": {    "type": "authentication_error",    "code": "unauthorized",    "message": "A valid API key is required.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/unauthorized.md"  }}

{  "error": {    "type": "authentication_error",    "code": "forbidden",    "message": "You do not have permission to perform this operation.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/forbidden.md"  }}

{  "error": {    "type": "not_found_error",    "code": "not_found",    "message": "The requested resource was not found.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/not_found.md"  }}

{  "error": {    "type": "conflict_error",    "code": "idempotency_in_progress",    "message": "A request with this idempotency key is still being processed.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/idempotency_in_progress.md"  }}

{  "error": {    "type": "rate_limit_error",    "code": "rate_limited",    "message": "Too many requests. Retry after the interval specified in the Retry-After header.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/rate_limited.md"  }}

{  "error": {    "type": "internal_error",    "code": "internal_error",    "message": "An unexpected error occurred while processing the request.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/internal_error.md"  }}

{  "error": {    "type": "internal_error",    "code": "idempotency_unavailable",    "message": "Idempotency storage is temporarily unavailable. Retry with the same idempotency key.",    "doc_url": "https://commet.co/docs/api-reference/2026-08-27/errors/idempotency_unavailable.md"  }}