added close button to message dialog

src/components/MessageDialog.tsx

@@ -35,7 +35,7 @@ export default function MessageDialog({
             centered
             backdrop={attributes.staticBackdrop ? 'static' : 'true'}
         >
-            <Modal.Header style={{ borderBottom: 'none' }}>
+            <Modal.Header style={{ borderBottom: 'none' }} closeButton>
                 {attributes.title && (
                     <Modal.Title>
                         <strong>{attributes.title}</strong>