[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

crates/ruff_linter/src/rules/flake8_datetimez/rules/call_date_today.rs

@@ -24,7 +24,7 @@ use crate::checkers::ast::Checker;
 /// ```python
 /// import datetime
 ///
-/// datetime.datetime.today()
+/// datetime.date.today()
 /// ```
 ///
 /// Use instead: