xxx component/qt: don't use version

component/qt/buildout.cfg

@@ -11,7 +11,6 @@ parts =
 # qmake binary can be reached directly from ${qt:location}/bin/qmake if [qt] is fully built
 recipe = slapos.recipe.cmmi
 location = ${buildout:parts-directory}/${:_buildout_section_name_}
-version = 5.6.2
 url = http://download.qt.io/official_releases/qt/5.6/5.6.2/single/qt-everywhere-opensource-src-5.6.2.tar.gz
 md5sum = 1b1b1f929d0cd83680354a0c83d8e945
 # see https://github.com/NixOS/nixpkgs/blob/3e387c3e005c87566b5403d24c86f71f4945a79b/pkgs/development/libraries/qt-4.x/4.8/default.nix#L101
@@ -41,7 +40,6 @@ post-install =
 # qmake binary can be reached directly from ${qt:location}/bin/qmake if [qt] is fully built
 recipe = slapos.recipe.cmmi
 location = ${buildout:parts-directory}/${:_buildout_section_name_}
-version = 4.8.7
 url = http://download.qt.io/official_releases/qt/4.8/4.8.7/qt-everywhere-opensource-src-4.8.7.tar.gz
 md5sum = d990ee66bf7ab0c785589776f35ba6ad
 # see https://github.com/NixOS/nixpkgs/blob/3e387c3e005c87566b5403d24c86f71f4945a79b/pkgs/development/libraries/qt-4.x/4.8/default.nix#L101