Just give a few puffs, or squirts of powder into the glass channel when the window is fully down...bring the window up to about halfway and repeat...the idea is to lubricate with talc powder, all of the channel. You might have to do it more than once...but it will work!
Let me be a smart arse for a moment...in your country, salt is used in the roads during winter, so salty spray on your windscreens and side windows is a common thing. That's why rust, among other problems are something you have learned to live with...how much salt collects on wipers, in window channels, on your vehicles undercarriage, buggers your paintwork etc? This crap (salt) is acidic, abrasive and just plain nasty...the faster you drive, the more of this rubbish gets forced into places it shouldn't be....when the weather warms up and the salt crystals form again...that's where your noise is coming from.
Thank God, salt is banned on Bulgarian roads...coarse river sand does a much better job!!