Update Emoji dataset to Unicode 14 (#22342)

Gitea emoji dataset was out of date because it gets manually built and
hasn't been rebuilt since it was added. This means Gitea doesn't
recognize some newer emoji or changes to existing ones.

After changing the max unicode version to 14 I just ran: `go run
build/generate-emoji.go`

This should address the initial issue seen in #22153 where Gitea doesn't
recognize a standard alias used elsewhere when importing content.

14 is the latest supported version from the upstream source as 15 is not
widely supported (in their opinion) yet

Author: mrsdizzie

assets/emoji.json

@@ -25,7 +25,7 @@ import (
 
 const (
 	gemojiURL         = "https://raw.githubusercontent.com/github/gemoji/master/db/emoji.json"
-	maxUnicodeVersion = 12
+	maxUnicodeVersion = 14
 )
 
 var flagOut = flag.String("o", "modules/emoji/emoji_data.go", "out")