Use FLAG_IMMUTABLE as required by android 12 (#366)

app/src/main/java/apps/amine/bou/readerforselfoss/background/background.kt

@@ -4,6 +4,7 @@ import android.app.NotificationManager
 import android.app.PendingIntent
 import android.content.Context
 import android.content.Intent
+import android.os.Build
 import android.preference.PreferenceManager
 import androidx.core.app.NotificationCompat
 import androidx.core.app.NotificationCompat.PRIORITY_DEFAULT
@@ -117,8 +118,12 @@ override fun doWork(): Result {
                     val intent = Intent(context, MainActivity::class.java).apply {
                         flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
                     }
-                    val pendingIntent: PendingIntent =
-                        PendingIntent.getActivity(context, 0, intent, 0)
+                    val pflags = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                        PendingIntent.FLAG_IMMUTABLE
+                    } else {
+                        0
+                    }
+                    val pendingIntent: PendingIntent = PendingIntent.getActivity(context, 0, intent, pflags)
 
                     val newItemsNotification =
                         NotificationCompat.Builder(applicationContext, Config.newItemsChannelId)