Fix email field in generated form HTML. Closes #529.

frontend/src/views/Forms.vue

@@ -41,7 +41,7 @@
         <pre v-if="checked.length > 0">&lt;form method=&quot;post&quot; action=&quot;{{ settings['app.root_url'] }}/subscription/form&quot; class=&quot;listmonk-form&quot;&gt;
     &lt;div&gt;
         &lt;h3&gt;Subscribe&lt;/h3&gt;
-        &lt;p&gt;&lt;input type=&quot;text&quot; name=&quot;email&quot; placeholder=&quot;{{ $t('subscribers.email') }}&quot; /&gt;&lt;/p&gt;
+        &lt;p&gt;&lt;input type=&quot;email&quot; name=&quot;email&quot; required placeholder=&quot;{{ $t('subscribers.email') }}&quot; /&gt;&lt;/p&gt;
         &lt;p&gt;&lt;input type=&quot;text&quot; name=&quot;name&quot; placeholder=&quot;{{ $t('public.subName') }}&quot; /&gt;&lt;/p&gt;
       <template v-for="l in publicLists"><span v-if="l.uuid in selected" :key="l.id" :set="id = l.uuid.substr(0, 5)">
         &lt;p&gt;