Update CHANGELOG for 5.4.18

Author: fabpot

CHANGELOG-5.4.md

@@ -7,6 +7,11 @@ in 5.4 minor versions.
 To get the diff for a specific change, go to https://github.com/symfony/symfony/commit/XXX where XXX is the change hash
 To get the diff between two versions, go to https://github.com/symfony/symfony/compare/v5.4.0...v5.4.1
 
+* 5.4.18 (2022-12-29)
+
+ * bug #48823 [Cache] Fix possibly null value passed to preg_match() in RedisTrait (chalasr)
+ * bug #48816 [Cache] Fix for RedisAdapter without auth parameter (rikvdh)
+
 * 5.4.17 (2022-12-28)
 
  * bug #48787 [PhpUnitBridge] Use verbose deprecation output for quiet types only when it reaches the threshold (ogizanagi)