release_schedule: Add release manager to 5.43.4

Author: thibaultduponchelle

Porting/release_schedule.pod

@@ -46,7 +46,7 @@ you should reset the version numbers to the next blead series.
   2025-07-20  5.43.1          Richard Leach
   2025-08-20  5.43.2          Ether
   2025-09-20  5.43.3
-  2025-10-20  5.43.4
+  2025-10-20  5.43.4          Max
   2025-11-20  5.43.5          Thibault
   2025-12-20  5.43.6
   2026-01-20  5.43.7          Thibault