Add `POST_NOTIFICATIONS` permission to app's manifest (#237)

Since we updated the target SDK version to 33 in
3f05b7fc1f, we should request
notifications permissions to continue allowing the user to receive
journal changes and certificate notifications

app/src/main/AndroidManifest.xml

@@ -23,6 +23,7 @@
     <uses-permission android:name="android.permission.READ_SYNC_STATS"/>
     <uses-permission android:name="android.permission.WRITE_SYNC_SETTINGS"/>
     <uses-permission android:name="android.permission.REQUEST_IGNORE_BATTERY_OPTIMIZATIONS"/>
+    <uses-permission android:name="android.permission.POST_NOTIFICATIONS"/>
 
     <!-- account management permissions not required for own accounts since API level 22 -->
     <uses-permission android:name="android.permission.AUTHENTICATE_ACCOUNTS" android:maxSdkVersion="22"/>