olex2: use correct reg path for version check etc

NB I know that in principle this change could leave some of my clients with a stale copy of the old/incorrect reg key. Given what I know about how (not) widespread usage of this package is, I'm happy to accept that for the sake of not making the wpkg needlessly complicated

approved this merge request

merged

mentioned in commit dad62f11

mentioned in issue #142 (closed)