Added missing test rss file (fixes test failure on update)

git-svn-id: http://framework.zend.com/svn/framework/standard/trunk@18348 44c647ce-9c0f-0410-b52a-842ac1e357ba

tests/Zend/Feed/Reader/Entry/_files/Rss/datemodified/plain/rss20-zf-7908.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<rss version="2.0">
+    <channel>
+        <item>
+            <pubDate>Sun, 11 Jan 2009 09:55:59 GMT</pubDate>
+        </item>
+    </channel>
+</rss>