release_schedule: Tick 5.43.0 - Add release manager to 5.43.1, 5.43.5, 5.43.7

Author: thibaultduponchelle

Porting/release_schedule.pod

@@ -42,14 +42,14 @@ you should reset the version numbers to the next blead series.
 
 =head2 Perl 5.43
 
-  2025-07-04  5.43.0                            (tag only)
-  2025-07-20  5.43.1
+  2025-07-04  5.43.0  ✓       Philippe          (tag only)
+  2025-07-20  5.43.1          Richard Leach
   2025-08-20  5.43.2
   2025-09-20  5.43.3
   2025-10-20  5.43.4
-  2025-11-20  5.43.5
+  2025-11-20  5.43.5          Thibault
   2025-12-20  5.43.6
-  2026-01-20  5.43.7
+  2026-01-20  5.43.7          Thibault
   2026-02-20  5.43.8                            Contentious changes freeze
   2026-03-20  5.43.9                            User-visible changes to
                                                 correctly functioning