[`flake8-datetimez`] Make `DTZ011` example error out-of-the-box (#19055)
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## Summary
<!-- What's the purpose of the change? What does it do, and why? -->
Part of #18972
This PR makes [call-date-today
(DTZ011)](https://docs.astral.sh/ruff/rules/call-date-today/#call-date-today-dtz011)'s
example error out-of-the-box
[Old example](https://play.ruff.rs/b42d6aef-7777-4b3b-9f96-19132000b765)
```py
import datetime
datetime.datetime.today()
```
[New example](https://play.ruff.rs/8577c3c1-cfa8-425b-b1e1-4c53b2a48375)
```py
import datetime
datetime.date.today()
```
## Test Plan
<!-- How was it tested? -->
N/A, no functionality/tests affected