Update to Unicode 18

[Jules-Bertholet]

No description provided.

[yhirose]

@Jules-Bertholet thank you for the update. That's exactly what I've been waiting for!

I verified this PR locally: regenerating with UNICODE_VERSION = (18, 0, 0) against the final 18.0.0 data produces a tables.rs that is byte-identical to the one here. No new EmojiStatus combinations or GeneralCategory values are needed, and cargo test --all-features and cargo fmt --all --check both pass with the new tables.

@Jules-Bertholet Would you mind adding a version bump to 0.1.5 in Cargo.toml, as #10 and #13 did? That would let this be released right after merging.

@Manishearth Could you approve the CI run and take a look when you have time?

Thanks!

[Manishearth]

Version bump should go in a different PR.

Looks like CI fails for unrelated reasons, but I'd like to be sure CI passes before merging.