fix(android-sdk): should not export LogtoWebViewAuthActivity (#204)

Author: xiaoyijun

android-sdk/android/src/main/AndroidManifest.xml

@@ -11,7 +11,7 @@
 
     <application>
         <activity android:name=".auth.logto.LogtoWebViewAuthActivity"
-            android:exported="true"
+            android:exported="false"
             android:configChanges="orientation|screenSize|keyboard|keyboardHidden"
             android:launchMode="singleTop" />