dependOnAssemble does not work with Fulladle

[kozaxinan]

Using dependOnAssemble with Fulladle tries to find TestedExtension in root project. TestedExtension is only part of Android libraries and application. Fulladle should ignore root module when dependOnAssemble is set to true.

* What went wrong:
Could not determine the dependencies of task ':runFlank'.
> Could not create task ':execFlank'.
   > Could not find TestedExtension in logistics-rider-app-android

Caused by: java.lang.IllegalArgumentException: Could not find TestedExtension in logistics-rider-app-android
        at com.osacky.flank.gradle.FladlePluginDelegate$createTasksForConfig$3.execute(FladlePluginDelegate.kt:125)
        at com.osacky.flank.gradle.FladlePluginDelegate$createTasksForConfig$3.execute(FladlePluginDelegate.kt:16)

Fladle 0.17.3

I checked the code and I thought of changing the logic of get method to find for TestedExtension to make it nullable and handle null case. If you guide me desired solution, I can open PR.