Bump version to 2.4.0. [ci skip]
Bump version to 2.4.0. [ci skip]

sadiqmmm/lita,MatthewKrey/lita,tristaneuan/lita,jimmycuadra/lita,PatrickTulskie/lita,byroot/lita,brodock/lita,liamdawson/lita,elia/lita,crimsonknave/lita,chriswoodrich/lita,chriswoodrich/lita,mcgain/lita,prsimp/lita,jimmycuadra/lita,mcgain/lita,natesholland/lita,natesholland/lita,litaio/lita,brodock/lita,MatthewKrey/lita,tristaneuan/lita,litaio/lita,crimsonknave/lita,elia/lita,liamdawson/lita,jaisonerick/lita,byroot/lita,jaisonerick/lita,sadiqmmm/lita