Bump changelog after updating to v6.12.15

Signed-off-by: Umer Saleem <usaleem@ixsystems.com>

Author: Umer Saleem

scripts/package/truenas/changelog

@@ -1,3 +1,9 @@
+linux-6.12.15+truenas (6.12.15+truenas-1) sid; urgency=low
+
+  * Merge upstream v6.12.15 release.
+
+ -- Debian Packages List <debian.packages@ixsystems.com>  Tue, 18 Feb 2025 17:00:00 +0500
+
 linux-6.12.9+truenas (6.12.9+truenas-1) sid; urgency=low
 
   * Merge upstream v6.12.9 release.