DOC: Start v1.4.3 release notes
```
2022-04-02T09:51:12.6852577Z WARNING: failed to reach any of the inventories with the following issues:
2022-04-02T09:51:12.6854196Z intersphinx inventory 'https://www.statsmodels.org/devel/objects.inv' not fetchable due to <class 'requests.exceptions.ConnectionError'>: HTTPSConnectionPool(host='www.statsmodels.org', port=443): Max retries exceeded with url: /devel/objects.inv (Caused by NewConnectionError('<urllib3.connection.HTTPSConnection object at 0x7f503e184f40>: Failed to establish a new connection: [Errno -3] Temporary failure in name resolution'))
```

