I have a similar concern, only I happened to purchase the game at gog.com, for which the version number is reported as 1.9.21, making it even older than the version that I now realise is carried by itch.io.
It is a little frustrating for those that would prefer to escape the clutches of Steam, in so far as one can never tell for which digital retail channels a given developer will be committed to delivering updates through. The only applicable rule of thumb seems to be: if it's available on Steam, expect not to receive updates in a timely fashion (if at all) elsewhere. I have no wish to use Steam but, even if I did, by having purchased it from gog.com, I cannot benefit from the use of a Steam key either.