Pr- Compatibility with SDK28

[HefnySco]

From November 1, 2019, app updates must target at least Android 9.0. Until this date, app updates must target at least Android 8.0 (API level 26) check here.

I faced this issue with my app and I made the updates based on here.

[HefnySco]

Guys,
I believe the build script needs to be reviewed.

* What went wrong:
A problem occurred configuring project ':ClientLib'.
> Failed to notify project evaluation listener.
   > You have not accepted the license agreements of the following SDK components:
     [Android SDK Platform 28].
     Before building your project, you need to accept the license agreements and complete the installation of the missing components using the Android Studio SDK Manager.
     Alternatively, to learn how to transfer the license agreements from one workstation to another, go to http://d.android.com/r/studio-ui/export-licenses.html
   > You have not accepted the license agreements of the following SDK components:
     [Android SDK Platform 28].
     Before building your project, you need to accept the license agreements and complete the installation of the missing components using the Android Studio SDK Manager.
     Alternatively, to learn how to transfer the license agreements from one workstation to another, go to http://d.android.com/r/studio-ui/export-licenses.html