[source-xero] Xero source is broken since 2.1.0. No records returned for streams

### Connector Name

source-xero

### Connector Version

2.1.0 - 2.1.4

### What step the error happened?

During the sync

### Relevant information

Xero source doesn't return any rows since version 2.1.0
It seems to make correct API calls that return payload with data
But no records are produced from these results

Version 2.0.1 works fine

### Relevant log output

```shell
INFO Starting syncing
INFO Marking stream contacts as STARTED
INFO Syncing stream: contacts
DEBUG Making outbound API request: {"url":"https://api.xero.com/api.xro/2.0/Contacts?page_size=100","request_body":"None","headers":"{'User-Agent': 'python-requests/2.32.3', 'Accept-Encoding': 'gzip, deflate', 'Accept': 'application/json', 'Connection': 'keep-alive', 'Xero-Tenant-Id': '****', 'Authorization': 'Bearer ****'}"}
DEBUG Receiving response: {"status":"200","body":"{\r\n \"Id\": \"****\",\r\n \"Status\": \"OK\",\r\n \"ProviderName\": \"****\",\r\n \"DateTimeUTC\": \"\\/Date(1758708209213)\\/\",\r\n \"Contacts\": [
... CONTACTS DATA ...
]\r\n}","headers":"{'Content-Type': 'application/json; charset=utf-8', 'Content-Length': '105019', 'Server': 'nginx', 'Xero-Correlation-Id': '****', 'X-AppMinLimit-Remaining': '9999', 'X-MinLimit-Remaining': '59', 'X-DayLimit-Remaining': '4993', 'Xero-Tenant-Id': '****', 'Expires': 'Wed, 24 Sep 2025 10:03:29 GMT', 'Cache-Control': 'max-age=0, no-cache, no-store', 'Pragma': 'no-cache', 'Date': 'Wed, 24 Sep 2025 10:03:29 GMT', 'Connection': 'keep-alive', 'X-Client-TLS-ver': 'tls1.3'}"}
INFO Read 0 records from contacts stream
INFO Marking stream contacts as STOPPED
INFO slice:{"start_time": "2025-01-01T00:00:00+0000", "end_time": "2025-09-24T10:03:28+0000"}
```

### Contribute

- [ ] Yes, I want to contribute