Add NQZ

[nsauk]

This is a rare case but IATA has changed the airport code of the capital of Kazakhstan (at the moment it's called Astana) from TSE to NQZ.

Sources:

• https://www.rferl.org/a/kazakh-capital-renamed-after-nazarbaev-changes-airport-code-to-nqz/30658764.html
• https://www.flightradar24.com/data/airports/nqz

I think we have to keep the line with the old IATA code too for a historical lookup.