Fix trigger fixture for `payment_method.detached` event

[vishal-sood]

Reviewers

r? @ cc @stripe/developer-products

Summary

Triggering the payment_method.detached event using the CLI (v1.20.0) is failing with the following error:

Trigger failed: Request failed, status=404, body={
  "error": {
    "code": "resource_missing",
    "doc_url": " https://stripe.com/docs/error-codes/resource-misssing",
    "message" "No such PaymentMethod: '${payment_method_attach.id}'; It's possible this PaymentMethod exists on one of your connected accounts, in which case you should retry this request on that connected account. Learn more at https://stripe.com/docs/connect/authentication",
    "param": "payment_method",
    "request_log_url": <redacted>,
    "type": "invalid_request_error"
  }
}

This PR updates the fixture which should resolve this issue!

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