try fix android manifest for high SDK

examples/android-chatter/src/main/AndroidManifest.xml

@@ -7,6 +7,7 @@
         android:label="@string/app_name"
         android:roundIcon="@mipmap/ic_launcher_round"
         android:supportsRtl="true"
+        android:exported="true"
         android:theme="@style/AppTheme">
         <activity android:name="io.libp2p.example.chat.MainActivity">
             <intent-filter>