Avoid whitespace in tags jhedstrom#600

Since Gherkin 4.9.0 tags with whitespace are deprecated: use a comma as
an explicit OR operator.

See
- Behat/Gherkin#213
- Behat/Gherkin#215
- https://behat.org/en/latest/user_guide/context/hooks.html#tagged-hooks

Closes jhedstrom#600

src/Drupal/DrupalExtension/Context/MailContext.php

@@ -44,7 +44,7 @@ public function enableMail($event)
    * Allow opting in to mail collection. When using the default mail manager
    * service, it is not necessary to use this tag.
    *
-   * @BeforeScenario @mail @email
+   * @BeforeScenario @mail,@email
    */
     public function collectMail()
     {
@@ -54,7 +54,7 @@ public function collectMail()
   /**
    * Stop collecting mail at scenario end.
    *
-   * @AfterScenario @mail @email
+   * @AfterScenario @mail,@email
    */
     public function stopCollectingMail()
     {
@@ -143,7 +143,7 @@ public function noNewMailIsSent($count, $to = '', $subject = '')
         $count = $count === 'an' ? 1 : $count;
         $this->assertMailCount($actualMail, $count);
     }
-  
+
   /**
    * @When I follow the link to :urlFragment from the (e)mail
    * @When I follow the link to :urlFragment from the (e)mail to :to