Write test for StripeConnectAccount.update_from_stripe/1

# Problem

Test should ensure the function returns an {:ok, %StripeConnectAccount{}} with valid data. It should also ensure that the record was actually updated with data from stripe testing.

An additional test should ensure that, if there is no local record with the specified `id_from_stripe`, the response is `{:error, :not_found}`

Lastly, a test should ensure that, if the attributes provided contain invalid data, an `{:error, changeset}` is returned.

### Something we cannot test right now, since we do not have the infrastructure
* If the stripe API raises an error, it returns `{:error, %StripeAPIErrorResponse{}}`

Locate StripeConnectAccount.update_from_stripe/1 and the surrounding test module, then run the existing account tests first. Done means tests cover valid updates, a missing id_from_stripe returning {:error, :not_found}, and invalid attributes returning an error changeset; Stripe API errors are explicitly out of scope.

由索引模型根据 Issue 内容生成。