Only show voter ID message when the postcode has an election

postcode_lookup/templates/result.html

@@ -82,10 +82,13 @@
     </style>
 
     <div class="dc-container">
+    {% if api_response.dates %}
     <p class="c-polling-station-slice">
         You’ll need to take photo ID with you if you’re voting at the polling station.
             <a href="https://www.electoralcommission.org.uk/i-am-a/voter/voter-id/accepted-forms-photo-id">Check the list of accepted forms of photo ID</a>.
     </p>
+    {% endif %}
+
         {% for date in api_response.dates %}
             <h2 class="o-type-h2">{{ date.date|date_filter }}</h2>
             <div class="dc-grid">