need a flush on some systems (otherwise content.xml will be empty)

Author: EQt

pyexcel_odsw/entrouvert_odsw.py

@@ -82,6 +82,7 @@ def close(self):
         xml.endTag()
         xml.endTag()
         xml.endTag()
+        self.content.file.flush()
         self.z.write(self.content.name, 'content.xml')
         self.content.close()
         self.z.close()