Annotation xytext property does not return xyann value

The deprecation wrapper [here](https://github.com/matplotlib/matplotlib/blob/c74dfa5d4a23ab66a308e405102fe126b7af1550/lib/matplotlib/text.py#L1646) needs to _return_ the `self.xyann` value.

```
    @property
    @cbook.deprecated('1.4', message='Use `xyann` instead',
                      name='xytext', alternative='xyann')
    def xytext(self):
        self.xyann
```
