Update hiredis-rb version number in README
Update hiredis-rb version number in README

dixiS/hiredis-rb,ferdinandrosario/hiredis-rb,redis/hiredis-rb,loggator/hiredis-rb,dixiS/hiredis-rb,redis/hiredis-rb,ferdinandrosario/hiredis-rb,loggator/hiredis-rb