Log Message:
unicode-character-database: update to 15.0.0.

Upstream changes:

15.0.0:
 https://www.unicode.org/versions/Unicode15.0.0/

Unicode 15.0 adds 4,489 characters, for a total of 149,186 characters.
These additions include 2 new scripts, for a total of 161 scripts,
along with 20 new emoji characters, and 4,193 CJK (Chinese, Japanese,
and Korean) ideographs.