File attach Cyrilic Name

Hello!

Found a mistake in the Contact Form 7 plugin. The problem was in file attach with filename in Russian lang. Looked at the forums and not found the right information, so I decided to try to fix it myself.

The result found that the error is in the file contact-form-7/modules/file.php when you convert a file name function wpcf7_canonicalize, but rather the function strtolower, which has a known problem with Cyrillic.
Replacing the function wpcf7_canonicalize the following code
if ( function_exists( ‘mb_convert_kana’ )
&& ‘UTF-8’ == get_option( ‘blog_charset’ ) ) {
$filename = mb_convert_kana( $filename, ‘asKV’, ‘UTF-8’ );
}
$filename = mb_strtolower( $filename);
$filename = trim( $filename);
the problem was solved.

I think that many users of your plugin will be grateful to you if you will make changes in the new version.