Duplicate ttf-parser dependency

[rparrett]

Tested 166b59f. This is also present in v0.12.1

ttf-parser v0.20.0
└── fontdb v0.16.2
    └── cosmic-text v0.12.1 (/Users/robparrett/src/cosmic-text)

ttf-parser v0.21.1
├── cosmic-text v0.12.1 (/Users/robparrett/src/cosmic-text)
└── rustybuzz v0.14.1 (*)

It looks like this will be fixed by #296 in its current state, but that PR is outdated now. However, the current latest releases of ttf-parser, fontdb, and rustybuzz are all aligned on ttf-parser 0.25, so this should continue to be the case if that PR gets updated.