PhabricatorMailImplementationPHPMailerLiteAdapter ignores parameter in setIsHTML

function.

Summary: Fix PhabricatorMailImplementationPHPMailerLiteAdapter to actually use
given parameter.

Test Plan: Use setIsHTML with false as parameter, sent mail should be in plain
text.

Reviewers: jungejason

Reviewed By: jungejason

CC: aran, jungejason, epriestley

Differential Revision: 1001

src/applications/metamta/adapter/phpmailerlite/PhabricatorMailImplementationPHPMailerLiteAdapter.php

@@ -75,7 +75,7 @@ class PhabricatorMailImplementationPHPMailerLiteAdapter
   }
 
   public function setIsHTML($is_html) {
-    $this->mailer->IsHTML(true);
+    $this->mailer->IsHTML($is_html);
     return $this;
   }