Add required mutability flag to PendingIntent

package net.fabiszewski.ulogger;

import static android.app.PendingIntent.FLAG_IMMUTABLE;

import android.app.Notification;

import android.app.NotificationChannel;

import android.app.NotificationManager;

        TaskStackBuilder stackBuilder = TaskStackBuilder.create(context);

        stackBuilder.addParentStack(MainActivity.class);

        stackBuilder.addNextIntent(resultIntent);

        PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, PendingIntent.FLAG_UPDATE_CURRENT);

        int flags = PendingIntent.FLAG_UPDATE_CURRENT;

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {

            flags |= FLAG_IMMUTABLE;

        }

        PendingIntent resultPendingIntent = stackBuilder.getPendingIntent(0, flags);

        mBuilder.setContentIntent(resultPendingIntent);

        Notification mNotification = mBuilder.build();

        notificationManager.notify(NOTIFICATION_ID, mNotification);