Specify OS X release .dmg name rather.
Specify OS X release .dmg name rather.

Previously it used the default Lasercake-{version}-Darwin.dmg,
but we release with Lasercake-{version}-OSX.dmg.

Lasercake/Lasercake,elidupree/Lasercake,idupree/Lasercake,elidupree/Lasercake,Lasercake/Lasercake,Lasercake/Lasercake,elidupree/Lasercake,idupree/Lasercake,idupree/Lasercake,idupree/Lasercake,elidupree/Lasercake,idupree/Lasercake,Lasercake/Lasercake,elidupree/Lasercake,elidupree/Lasercake,idupree/Lasercake,Lasercake/Lasercake,idupree/Lasercake,elidupree/Lasercake