Docker: update ruby to 2.4
Docker: update ruby to 2.4

eugenesvk/huginn,mathias/huginn,younata/huginn,Ishfal/huginn,virtadpt/huginn,Ishfal/huginn,younata/huginn,huginn/huginn,cantino/huginn,virtadpt/huginn,brianpetro/huginn,eugenesvk/huginn,mathias/huginn,cantino/huginn,mathias/huginn,gautamkrishnar/huginn,brianpetro/huginn,huginn/huginn,naiyt/huginn,johnleeming/huginn,younata/huginn,dsander/huginn,breandan/huginn,strugee/huginn,strugee/huginn,cantino/huginn,eugenesvk/huginn,johnleeming/huginn,breandan/huginn,dsander/huginn,gautamkrishnar/huginn,Ishfal/huginn,CodeHunter2006/huginn,breandan/huginn,virtadpt/huginn,naiyt/huginn,naiyt/huginn,dsander/huginn,johnleeming/huginn,huginn/huginn,CodeHunter2006/huginn,strugee/huginn,brianpetro/huginn,gautamkrishnar/huginn,CodeHunter2006/huginn