std.uni has been upgraded from Unicode 15.1.0 to 16.0.0

This Unicode update was released September 10, 2024, and adds new blocks with characters.
See: https://www.unicode.org/versions/Unicode16.0.0/

```
import std;

void main()
{
    const alphaCount = iota(0, dchar.max).filter!(std.uni.isAlpha).walkLength;
    writeln(alphaCount);
    // formerly: 138387
    // now:      142759
}
```
