Binja does not close the dyld cache files when the database is closed

5.3.8953-dev
non-regression afaik

```
Unmount of disk7 failed: at least one volume could not be unmounted
Unmount was dissented by PID 57146 (/Applications/Binary Ninja.app/Contents/MacOS/binaryninja)
Dissenter parent PPID 1 (/sbin/launchd)
```