Replace `convert` with `*-config` to get ImageMagick version
Replace `convert` with `*-config` to get ImageMagick version

This is because GraphicsMagick has `convert` and it might be called.

tvon/rmagick,carsonreinke/rmagick,antonifs/rmagick,jonmartindell/rmagick,rmagick/rmagick,rmagick/rmagick,tvon/rmagick,rmagick/rmagick,jonmartindell/rmagick,tvon/rmagick,carsonreinke/rmagick,jonmartindell/rmagick,antonifs/rmagick,antonifs/rmagick,carsonreinke/rmagick