Merge pull request #5143 from matsuoshi/modify-file-form-style

class名指定時の崩れを修正

src/Eccube/Resource/template/admin/Form/bootstrap_4_horizontal_layout.html.twig

@@ -46,6 +46,6 @@ file that was distributed with this source code.
 {% endblock %}
 
 {%- block file_widget -%}
-    {%- set attr = attr|merge({class: (attr.class|default('') ~ 'form-control-file')|trim}) -%}
+    {%- set attr = attr|merge({class: (attr.class|default('') ~ ' form-control-file')|trim}) -%}
     <input type="file" {{ block('widget_attributes') }} {% if value is not empty %}value="{{ value }}" {% endif %}/>
 {%- endblock -%}