INVALID mark up 1.2.8.7

Just trying to validate my code (for better seo results) and the http://validator.w3.org throw this message

line 18, Column 16: there is no attribute “property”

<meta property=’og:locale’ content=’en_US’/>

after search for this the code is generated at

/public_html/wp-content/plugins/wordpress-seo/frontend/class-opengraph.php

Any plans on updating to produce valid code?

or how can I remove this line?

thanks

http://ww.wp.xz.cn/extend/plugins/wordpress-seo/