Update Cirq versions in dev_tools/write-ci-requirements.py

Near the top of the file, we see

```python
CIRQ_VERSIONS = {
    'previous': '~=1.2.0',
    'current': '~=1.3.0',
    'next': '>=1.4.0.dev',
}
```

This should be updated. We can probably wait until the release of Cirq 1.5, because it will be very soon.