Ensure all <package> elements have a fully-qualified xmlns

All the newer packages that we've added have consistently and correctly specified the xmlns on the element but some of the earlier ones we put in did not. I've just gone through and updated all the packages where this was missing.

packages/7zip.xml

 <?xml version="1.0" encoding="UTF-8"?>
 
-<packages>
+<packages:packages xmlns:packages="http://www.wpkg.org/packages">
 
   <package id="7zip" name="7-Zip" revision="%version%.1" reboot="false" priority="0">
     <variable name="version" value="19.00" />
@@ -31,4 +31,4 @@
     </remove>
 
   </package>
-</packages>
+</packages:packages>