Add android:exported attribute to AndroidManifest

[sebastinto]

I believe I am getting Manifest Merger errors because of the missing attribute in this lib.

Please see Android Dev documentation:

If your app targets Android 12 and contains activities, services, or broadcast receivers that use intent filters, you must explicitly declare the android:exported attribute for these app components.

I set the attribute to "true" in this PR but setting it to "false" would also fix compatibility with Android 12.

[deva666]

Thanks!

[sebastinto]

Actually, after having a conversation about these errors with @mikepenz, I found out that this library was not causing the issue. You do not need to add the android:exported attribute. Please see HERE for an explanation. Sorry about the trouble.