patch 9.0.0587: Unicode tables are outdated

Problem:    Unicode tables are outdated.
Solution:   Update to Unicode release 15. (Christian Brabandt, closes #11220)
diff --git a/runtime/tools/unicode.vim b/runtime/tools/unicode.vim
index 6da013e..aa260e6 100644
--- a/runtime/tools/unicode.vim
+++ b/runtime/tools/unicode.vim
@@ -462,8 +462,9 @@
 call BuildWidthTable('A', 'ambiguous')
 
 " Edit the emoji text file.  Requires the netrw plugin.
-edit https://unicode.org/Public/emoji/12.1/emoji-data.txt
-
-" Build the emoji table. Ver. 1.0 - 6.0
-" Must come after the "ambiguous" and "doublewidth" tables
-call BuildEmojiTable()
+" commented out, because it drops too many characters
+"edit https://unicode.org/Public/15.0.0/ucd/emoji/emoji-data.txt
+"
+"" Build the emoji table. Ver. 1.0 - 6.0
+"" Must come after the "ambiguous" and "doublewidth" tables
+"call BuildEmojiTable()