fix(sdk): return transactionHash from cancelOrder method

[Lesnak1]

Summary

Fixes #1981.

Ensures the singular cancelOrder method returns the transactionHash string, aligning its return interface behavior with cancelOrders.

Rationale

Allows developers to receive and track the transaction hash immediately after initiating single order cancellations.

Verification

• Built locally via npm run build (tsc) without errors.
• Verified against unit test suite (npm test): 791/791 tests passed cleanly.

[socket-security]

No dependency changes detected. Learn more about Socket for GitHub.

👍 No dependency changes detected in pull request

[ryanio]

Thanks @Lesnak1, appreciate you taking this on. It duplicates #1982, which landed the same fix for #1981 a couple of weeks earlier, so we've carried that one into our internal source repo with credit to its author.

The fix will go out in the next @opensea/sdk release. Closing this as a duplicate, and thanks again for the contribution.