fix display of time in assigment log (now a timestamp), fixes #5370

Closes #5370

Merge request studip/studip!4050

app/controllers/vips/solutions.php

@@ -732,7 +732,7 @@ class Vips_SolutionsController extends AuthenticatedController
                     $assignment_attempt->user->vorname,
                     $assignment_attempt->user->username,
                     $entry['label'],
-                    $entry['time'],
+                    date('Y-m-d H:i:s', $entry['time']),
                     $entry['ip_address'],
                     $entry['ip_address'] ? $this->gethostbyaddr($entry['ip_address']) : '',
                     $entry['session_id']

app/views/vips/solutions/show_assignment_log.php

@@ -37,7 +37,7 @@
                     <?= htmlReady($log['label']) ?>
                 </td>
                 <td>
-                    <?= date('d.m.Y, H:i:s', strtotime($log['time'])) ?>
+                    <?= date('d.m.Y, H:i:s', $log['time']) ?>
                 </td>
                 <td>
                     <?= htmlReady($log['ip_address']) ?>