all: CHANGELOG update for release v2.5.6

Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>
(imported from commit 883a62cc)
Signed-off-by: Paul Moore <paul@paul-moore.com>

CHANGELOG

@@ -30,6 +30,12 @@ https://github.com/seccomp/libseccomp
 - Many test and CI improvements and fixes
 - Many documentation improvements and updates
 
+* Version 2.5.6 - January 24, 2025
+- Update the syscall table for Linux v6.13
+- Fix a bug where the internal filter state could be corrupted when a filter
+  rule addition fails
+- Fix potential memory leak in the internal management of filter snapshots
+
 * Version 2.5.5 - December 1, 2023
 - Update the syscall table for Linux v6.7-rc3