Release testing instructions for WC Payments 9.1.0

fix: Manual capture fails in the transaction detail screen with a customized order number

PR https://github.com/Automattic/woocommerce-payments/pull/10435

1. Install and activate a sequential order number plugin (like Sequential Order Numbers for WooCommerce or Sequential Order Numbers Pro for WooCommerce, which can be downloaded from here by any Automattic staff)
2. Create a new order with a payment that requires manual capture
3. Try to capture the payment from the transaction detail screen
4. Verify that the capture succeeds and no errors occur
5. Verify that order and subscription numbers are displayed correctly in the transactions list