Update testpress SDK version to 1.3.18
Update testpress SDK version to 1.3.18

- Support languages field in exam field to be null.
- Support setting video speed rate in exo player.
- Restrict video playing while mobile connected to a USB.
- Display video in exo player using dialog instead of new activity.
- Support mp4 video resume on the place where user left last time.

testpress/android,testpress/android,testpress/android,testpress/android,testpress/android