Removes redundant notifyListeners() call from _deleteBooking().
The method is executed through Command, which already manages its own
notifyListeners lifecycle. This change ensures that HomeViewModel
only notifies listeners when its internal state (_bookings) changes,
avoiding unnecessary updates.
Fixes https://github.com/flutter/samples/issues/2746
## Pre-launch Checklist
- [x] I read the [Flutter Style Guide] recently, and have followed its
advice.
- [x] I signed the [CLA].
- [ ] I have added sample code updates to the [changelog].
- [ ] I updated/added relevant documentation (doc comments with `///`).
<!-- Links -->
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/master/docs/contributing/Style-guide-for-Flutter-repo.md
[CLA]: https://cla.developers.google.com/
[changelog]: ./CHANGELOG.md
Co-authored-by: Eric Windmill <eric@ericwindmill.com>
