I downloaded Sketch 45.1. The I made a copy of my previous version of Sketch to my desktop. Then I uninstalled previous version of Sketch with AppCleaner - I checked all options, so everything should be deleted.
Finally I opened Sketch 45.1 - I moved it into my Applications folder and Sketch didn't opened. At all. I also used Trip Mode app to block any internet connection which could Sketch possible made. Didn't help.