Fix all subEntities method visibility.

src/Entities/CallbackQuery.php

@@ -30,7 +30,7 @@ class CallbackQuery extends Entity
     /**
      * {@inheritdoc}
      */
-    public function subEntities()
+    protected function subEntities()
     {
         return [
             'from'    => User::class,

src/Entities/Chat.php

@@ -46,7 +46,7 @@ class Chat extends Entity
     /**
      * {@inheritdoc}
      */
-    public function subEntities()
+    protected function subEntities()
     {
         return [
             'photo'          => ChatPhoto::class,

src/Entities/ChatMember.php

@@ -38,7 +38,7 @@ class ChatMember extends Entity
     /**
      * {@inheritdoc}
      */
-    public function subEntities()
+    protected function subEntities()
     {
         return [
             'user' => User::class,

src/Entities/Payments/OrderInfo.php

@@ -29,7 +29,7 @@ class OrderInfo extends Entity
     /**
      * {@inheritdoc}
      */
-    public function subEntities()
+    protected function subEntities()
     {
         return [
             'shipping_address' => ShippingAddress::class,

src/Entities/Payments/PreCheckoutQuery.php

@@ -34,7 +34,7 @@ class PreCheckoutQuery extends Entity
     /**
      * {@inheritdoc}
      */
-    public function subEntities()
+    protected function subEntities()
     {
         return [
             'from'       => User::class,

src/Entities/Payments/ShippingQuery.php

@@ -31,7 +31,7 @@ class ShippingQuery extends Entity
     /**
      * {@inheritdoc}
      */
-    public function subEntities()
+    protected function subEntities()
     {
         return [
             'from'             => User::class,

src/Entities/Payments/SuccessfulPayment.php

@@ -32,7 +32,7 @@ class SuccessfulPayment extends Entity
     /**
      * {@inheritdoc}
      */
-    public function subEntities()
+    protected function subEntities()
     {
         return [
             'order_info' => OrderInfo::class,