Fix bug when manifest is merged.

[StephaneBg]

Update build tools.

Remove android:allowBackup="true" from manifest to fix this issue:

Error:Execution failed for task ':app:processDebugManifest'. Manifest merger failed : Attribute application@allowBackup value=(false) from AndroidManifest.xml:9:9-36 is also present at [io.palaima:smoothbluetooth:0.1.0] AndroidManifest.xml:12:9-35 value=(true). Suggestion: add 'tools:replace="android:allowBackup"' to element at AndroidManifest.xml:8:5-40:19 to override.