[library decryption dialog] fixed the 'close' icon after the upgrade of seafile-ui.css (#7654)

frontend/src/components/common/seahub-modal-close.js

@@ -0,0 +1,15 @@
+import React from 'react';
+import { gettext } from '../../utils/constants';
+import '../../css/seahub-modal-header.css';
+
+const SeahubModalCloseIcon = (props) => {
+  return (
+    <button type="button" className={`close seahub-modal-btn ${props.className ? props.className : ''}`} data-dismiss="modal" aria-label={gettext('Close')} onClick={props.toggle}>
+      <span className="seahub-modal-btn-inner">
+        <i className="sf3-font sf3-font-x-01" aria-hidden="true"></i>
+      </span>
+    </button>
+  );
+};
+
+export default SeahubModalCloseIcon;