Fix Timber's package name

Timber's package name is actually just naman14.timber, instead of com.naman14.timber.

References:

• https://github.com/naman14/Timber/blob/master/app/build.gradle
• https://f-droid.org/wiki/page/naman14.timber
• https://play.google.com/store/apps/details?id=naman14.timber