Update the gemspec for the 3.1.1 release
Update the gemspec for the 3.1.1 release

vmg/redcarpet,Hacker0x01/redcarpet,gitcafe-dev/redcarpet,increments/greenmat,vmg/redcarpet,increments/greenmat,liquorburn/redcarpet,kaneshin/redcarpet,Hacker0x01/redcarpet,vmg/redcarpet,Hacker0x01/redcarpet,kattybilly/redcarpet,increments/greenmat,emq/redcarpet,fukayatsu/redcarpet,emq/redcarpet,kattybilly/redcarpet,fukayatsu/redcarpet,kaneshin/redcarpet,JuanitoFatas/redcarpet,be9/redcarpet,gitcafe-dev/redcarpet,emq/redcarpet,JuanitoFatas/redcarpet,fukayatsu/redcarpet,liquorburn/redcarpet,emq/redcarpet,JuanitoFatas/redcarpet,increments/greenmat,kaneshin/redcarpet,be9/redcarpet,vmg/redcarpet,liquorburn/redcarpet,be9/redcarpet,Hacker0x01/redcarpet,kaneshin/redcarpet,kattybilly/redcarpet,liquorburn/redcarpet,gitcafe-dev/redcarpet,be9/redcarpet,kattybilly/redcarpet,fukayatsu/redcarpet