themes/alps: fix search form method

themes/alps/messages-header.html

@@ -24,7 +24,7 @@
         <a href="{{ .GlobalData.URL.String }}" class="button-link">Refresh</a>
       </div>
 
-      <form action="" method="post" class="actions-search">
+      <form action="" method="get" class="actions-search">
         <input type="text" name="query" value="{{.Query}}" placeholder="Search messages...">
         <button>Search</button>
       </form>