Update APNet deadline (#1386)

Author: sarendis56

conference/NW/apnet.yml

@@ -29,7 +29,7 @@
       id: apnet26
       link: https://conferences.sigcomm.org/events/apnet2026/
       timeline:
-        - deadline: '2026-03-06 23:59:59'
+        - deadline: '2026-03-11 23:59:59'
       timezone: AoE
       date: August 6-7, 2026
       place: Singapore