Fix null pointer

[J-Jamet]

• Fix to prevent null pointer (issue Null exception with keyboard validation #421)
• Gradle update
• Fix lib versions which are not identical (Last manual versions are preferred and are compatible with other AndroidX libraries : https://developer.android.com/jetpack/androidx/releases/annotation - https://developer.android.com/jetpack/androidx/releases/appcompat)

[mgod]

Thank you! I'll try to get a new release put together in the next week or so.

[J-Jamet]

I will add the corrected sources to the KeePassDX app until the library is updated.

[rezazarchi]

Please merge this commit. We have a crash in our app with this library when clicking next or any action on keyboard.