Bump syncfusion_flutter_calendar from 23.2.5 to 23.2.6 (#2183)

Bumps [syncfusion_flutter_calendar](https://github.com/syncfusion/flutter-widgets/tree/master/packages) from 23.2.5 to 23.2.6.
- [Release notes](https://github.com/syncfusion/flutter-widgets/releases)
- [Commits](https://github.com/syncfusion/flutter-widgets/commits/HEAD/packages)

---
updated-dependencies:
- dependency-name: syncfusion_flutter_calendar
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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