Fixed date format consistency in presskit.

Author: GoogleFrog

presskit/data.xml

@@ -3,7 +3,7 @@
 <game>
 	<title>Zero-K</title>
 	<founding-date>October 1, 2010</founding-date>
-	<release-date>27 April, 2018</release-date>
+	<release-date>April 27, 2018</release-date>
 	<website>zero-k.info</website>
 	<based-in>International</based-in>
 	<press-can-request-copy>TRUE</press-can-request-copy>