feat(Australia): refresh holiday rules and rename Queen's Birthday to Monarch's Birthday

[aaronflorey]

Summary

• update Australian state and territory providers to reflect current holiday rules and timezone handling
• rename Queen's Birthday references to Monarch's Birthday and add the new translation data
• add and update coverage for regional holiday behavior, including Anzac Day Monday observance and Easter Sunday/Saturday cases where applicable

Testing

• existing Australia provider tests updated to cover the revised holiday definitions
• new tests added for state- and region-specific edge cases across affected providers

[stelgenhof]

@aaronflorey Thank you so much! I have reviewed your PR and it is looking very solid. The only few (non-critical) observations are these

• Consider adding a deprecated alias (queensBirthday → monarchsBirthday) to ease migration for downstream consumers
• Extract year thresholds (2023, 2024, etc.) into constants for easier maintenance

e.g.:

    private const MONARCHY_CHANGE_YEAR = 2023;
    private const SA_EASTER_SUNDAY_YEAR = 2024;

• Add specific test for 2022–2023 transition to verify both holiday names appear correctly

[stelgenhof]

Thanks for the last improvements! All looking very good. There is one small issue left (DCO): see https://github.com/azuyalabs/yasumi/pull/410/checks. Once that is taken care of, it can be merged