knotserver: fix sort order of tags

the output produced by for-each-rev is lexicographic.

Signed-off-by: oppiliappan <[e-mail]>

knotserver/git/tag.go

···
 		tags = append(tags, tag)
 	}
 
-	slices.Reverse(tags)
+	slices.SortFunc(tags, func(a, b object.Tag) int {
+		if a.Tagger.When.After(b.Tagger.When) {
+			return -1
+		}
+		if b.Tagger.When.After(a.Tagger.When) {
+			return 1
+		}
+		return 0
+	})
+
 	return tags, nil
 }