Update airports.csv

Author: mapcat

air/data/airports.csv

@@ -1,5 +1,5 @@
 country;iata_code;name;latitude;longitude;alt_codes
-ABW;AUA;Queen Beatrix International Airport;12.5014;-70.0153;nul
+ABW;AUA;Queen Beatrix International Airport;12.5014;-70.0153;null
 AUS;ASP;Alice Springs Airport;-23.8045;133.8953;
 AUS;AYQ;Ayers Rock Airport;-25.1861;130.9756;
 AUS;CNS;Cairns Airport;-16.8747;145.7542;