Drop Mitra Mono from 65-nonlatin.conf

This font seems totally broken.

Fixes fontconfig/fontconfig#128
2 jobs for <span class="ref-name">issue/128</span> in 8 minutes and 29 seconds
Status Job ID Name Coverage
  Build
passed #36674
shared-build

00:08:29

passed #36675
static-build

00:07:30