Update reg path used by installer to ucam_wpkg variant

NB 2.45.1 also adds procmon to the set of tools

see also

https://gitlab.developers.cam.ac.uk/ch/co/wpkg/pstools-nsis/-/commit/d016bd55c7a70c37dde48dc3ebb2b5cde21ebf4e

packages/pstools.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <packages>
   <package id="pstools" name="PSTools" revision="%version%.1" priority="0" reboot="false">
-    <variable name="version" value="2.45" />
+    <variable name="version" value="2.45.1" />
 
-    <check type='logical' condition='or'>
-      <check type='registry' condition='equals' path='HKLM\software\wow6432node\ch.cam.ac.uk\WPKG\pstools' value="%version%"/>
-      <check type='registry' condition='equals' path='HKLM\software\ch.cam.ac.uk\WPKG\pstools' value="%version%"/>
-    </check>
+    <!-- N.B. the installer takes care of creating and removing this reg key as needed -->
+    <check type='registry' condition='equals' path='HKLM\software\ucam_wpkg.cam.ac.uk\pstools\version' value="%version%"/>
 
     <!-- the exe is built by https://gitlab.developers.cam.ac.uk/ch/co/wpkg/pstools-nsis; see README contained therein -->