Try "Verify / Repair" - the 1.01.20 patch updated for me automatically about an hour or two just before release and can be seen correct here, so it's there for sure, it might be an issue with GOG Galaxy rather than the game itself.
The installer files also seem to be updated to the later patch as expected (as seen here from the web page with the proper version in the second column). I in fact re-installed the game today using those.