Dependency Guard treats unresolved dependencies as removed

Hi!
There are cases when dependency is not being resolved (for instance because repository like jitpack.io is currently down).
I'd expect this plugin to fail the build with proper error like "could not resolve dependency ..."
But now it instead treats unresolved dependency as removed:

```
> Task :app:dependencyGuard
Dependencies Changed in :app for configuration gmsReleaseRuntimeClasspath
- com.github.inappstory:android-sdk-utilsconnector:1f1a1925cb3e7f03e08040683213d5bfdfc46bcc
- com.github.instacart:truetime-android:4.0.0.alpha
- com.github.yalantis:ucrop:2.2.9
```