patch applied (packages/pretty): Require Cabal version >= 1.6

[Ian Lynagh]

Wed Jan 21 17:13:20 PST 2009  Ian Lynagh <igloo at earth.li>
  * Require Cabal version >= 1.6

    M ./pretty.cabal -1 +1

View patch online:
http://darcs.haskell.org/packages/pretty/_darcs/patches/20090122011320-3fd76-d88a721401652bc6220fdab619604001b611325f.gz