Media: Remove required attribute from media uploader file input field.

This commit removes the `required` attribute from the file input element in the media uploader to avoid browser form validation issues and ensure that the `form` element is submitted correctly.

Props adamsilverstein, ellatrix, desrosj, huzaifaalmesbah, immeet94, krupajnanda, madhavishah01, parthvataliya, ravichudasama01, sabernhardt, wildworks, yagniksangani. 
Fixes #64305.

git-svn-id: https://develop.svn.wordpress.org/trunk@61320 602fd350-edb4-49c9-b593-d223f7449a82

Author: t-hamano

src/wp-admin/includes/media.php

@@ -2285,7 +2285,7 @@ function media_upload_form( $errors = null ) {
 			_ex( 'Upload', 'verb' );
 			?>
 		</label>
-		<input type="file" name="async-upload" id="async-upload" required />
+		<input type="file" name="async-upload" id="async-upload" />
 		<?php submit_button( _x( 'Upload', 'verb' ), 'primary', 'html-upload', false ); ?>
 		<a href="#" onclick="try{top.tb_remove();}catch(e){}; return false;"><?php _e( 'Cancel' ); ?></a>
 	</p>