Fix `luarocks list --outdated`
Fix `luarocks list --outdated`

Compare latest available version with latest installed version,
not with lexicographically smallest installed version.

robooo/luarocks,xpol/luavm,robooo/luarocks,xpol/luarocks,robooo/luarocks,keplerproject/luarocks,xpol/luarocks,luarocks/luarocks,keplerproject/luarocks,robooo/luarocks,keplerproject/luarocks,xpol/luainstaller,xpol/luavm,xpol/luainstaller,luarocks/luarocks,xpol/luarocks,xpol/luavm,tarantool/luarocks,xpol/luarocks,keplerproject/luarocks,luarocks/luarocks,xpol/luainstaller,xpol/luavm,xpol/luavm,tarantool/luarocks,xpol/luainstaller,tarantool/luarocks