Upgrade deprecated classes

• /htmlmail.info.yml
• /htmlmail.module
• /src/Form/HtmlMailConfigurationForm.php
• /src/Form/HtmlMailTestForm.php
• /src/Helper/HtmlMailHelper.php
• /src/Plugin/Mail/HtmlMailSystem.php
• /src/Utility/HtmlMailMime.php
• /htmlmail.services.yml

src/Form/HtmlMailConfigurationForm.php

@@ -6,11 +6,11 @@ use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Form\ConfigFormBase;
 use Drupal\Core\Form\FormStateInterface;
-use Symfony\Component\DependencyInjection\ContainerInterface;
 use Drupal\htmlmail\Helper\HtmlMailHelper;
+use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
- * Class HtmlMailConfigurationForm.
+ * Form to configure HtmlMail.
  *
  * @package Drupal\htmlmail\Form
  */