[ruby/date] Remove unneeded line in update-abbr

https://github.com/ruby/date/commit/ae14e5f293

bin/update-abbr

@@ -29,7 +29,6 @@ lines.select{|l| l.include?(',')}.
   map{|l| l.split(',', 2)[0]}.
   each{|a| h.delete(a)}
 
-h.sort.map{|k,v| "#{k},#{v}"}
 lines.insert(-2, h.sort.map{|k,v| "#{k},#{v}\n"})
 lines.flatten!
 File.write('ext/date/zonetab.list', lines.join)