Add `payment_details.payment_method_name` to transactions.json

[rjh336]

Description of change

payment_details.payment_method_name was added to the transactions spec in Shopify Admin API v2024-01 https://shopify.dev/docs/api/admin-rest/2024-01/resources/transaction#resource-object

QA steps

• [ ] automated tests passing
• [ ] manual qa steps passing (list below)

Risks

Rollback steps

• revert this branch

[rjh336]

cc @HarrisonMarcRose @bhtowles