Use default notification priority

app/src/main/java/eu/faircode/email/ServiceSynchronize.java

@@ -375,7 +375,7 @@ public class ServiceSynchronize extends LifecycleService {
                 .setNumber(messages.size())
                 .setShowWhen(false)
                 .setDeleteIntent(piClear)
-                .setPriority(Notification.PRIORITY_HIGH)
+                .setPriority(Notification.PRIORITY_DEFAULT)
                 .setCategory(Notification.CATEGORY_STATUS)
                 .setVisibility(Notification.VISIBILITY_PRIVATE)
                 .setGroup(BuildConfig.APPLICATION_ID)
@@ -457,7 +457,7 @@ public class ServiceSynchronize extends LifecycleService {
                     .setSound(uri)
                     .setWhen(message.sent == null ? message.received : message.sent)
                     .setDeleteIntent(piDelete)
-                    .setPriority(Notification.PRIORITY_HIGH)
+                    .setPriority(Notification.PRIORITY_DEFAULT)
                     .setCategory(Notification.CATEGORY_STATUS)
                     .setVisibility(Notification.VISIBILITY_PRIVATE)
                     .setGroup(BuildConfig.APPLICATION_ID)