Remove *.bin glob from disc images

*.bin is too generic to be used for specific file types. As the file
managers should be able to detect the Sega CD and Sega Saturn disc
images by magic, we shouldn't be losing any convenience.

Closes: #101
1 job for master in 2 minutes and 53 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test
passed #518340
build

00:02:53