Updated native version to 1.21.8

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Migrate `Date` to `VenturaCalendarDate` across the codebase. Refactor corresponding methods, classes, and placeholder logic. Remove unused `Date` class and update imports. Enhancements include the addition of `@Getter`, `@Setter`, and `@AllArgsConstructor` annotations, replacing manual getter/setter implementations. Streamline event handling with better usage of enums, `SimpleDateFormat`, and placeholder registration. Improve code readability, consistency, and modernization.