Gotta make sure whoever installed it used expansion joints or slip clips, not fixed fasteners. If they screwed the panels tight into the purlins without allowing for movement, that noise is just gonna keep happening. I had a buddy in Calgary who fixed this by swapping out some of the fixed clips for slide clips, especially on the longer panels. Also check if they left enough room at the eave and ridge for the panels to grow and shrink. If everything's too tight, you're basically trapping the metal and it'll pop and ping till it finds a way to move. Thicker gauge metal helps too, 24 gauge is way quieter than the thin 26 or 28 stuff.

Ah man, that's the worst. I spent two days on one in my hallway last year. Pried up a whole section of plywood trying to find it. Turned out to be a loose nail right next to a joist. Just hammered it back down and the squeak was gone. Such a simple fix after all that work.