Android build failure (Could not determine java version)

`gradelw` calls fail with messages:

```
FAILURE: Build failed with an exception.

* What went wrong:
Could not determine java version from '11.0.9'.
```

Need to upgrade used gradle version to support JDK 11.
- 5.0+ according to https://docs.gradle.org/5.0/release-notes.html#java-11-runtime-support