Add missing field to contact form email template

public/typo3conf/ext/ep_theme/Resources/Private/Templates/Email/ContactForm.html

@@ -15,6 +15,10 @@
                 <th>Name</th>
                 <td>{contactForm.name}</td>
             </tr>
+            <tr>
+                <th>Vorname</th>
+                <td>{contactForm.firstName}</td>
+            </tr>
             <tr>
                 <th>Geschlecht</th>
                 <td>{contactForm.gender}</td>