Update deadline for PRCV 2026 conference (#1473)

Author: Lukangkang123

conference/CG/prcv.yml

@@ -36,7 +36,7 @@
       id: prcv26
       link: https://www.prcv.cn/web/#/home
       timeline:
-        - deadline: '2026-04-15 23:59:59'
+        - deadline: '2026-04-30 23:59:59'
       timezone: UTC+8
       date: Aug 22-25, 2026
       place: Harbin, China