fix: add max username length of 39 chars

Author: wildan3105

src/pages/partials/body.handlebars

@@ -13,7 +13,7 @@
           <form id="search-form" action="" method="get" action="#">
             <div class="input-group">
               <input type="text" class="form-control" autofocus="autofocus" id="username" name="username" placeholder="Github username"
-                required title="Username cannot be empty or contain only spaces">
+                required title="Username cannot be empty or contain only spaces" maxlength="39">
               <button type="submit" class="input-group-addon btn" name="" onClick="return validateInput();">
                 <i class="fa fa-search"></i>
               </button>