Porting: change the release manager of 5.43.3

Author: thibaultduponchelle

Porting/release_schedule.pod

@@ -45,7 +45,7 @@ you should reset the version numbers to the next blead series.
   2025-07-04  5.43.0  ✓       Philippe Bruhat   (tag only)
   2025-07-20  5.43.1  ✓       Richard Leach
   2025-08-20  5.43.2  ✓       Karen Etheridge
-  2025-09-20  5.43.3          Philippe Bruhat
+  2025-09-20  5.43.3          Thibault Duponchelle
   2025-10-20  5.43.4          Eric Herman
   2025-11-20  5.43.5          Thibault Duponchelle
   2025-12-20  5.43.6          Steve Hay