Update CHANGELOG.md

Co-authored-by: kenjis <[email protected]>

Author: MGatner

CHANGELOG.md

@@ -3,7 +3,7 @@
 ## [v4.2.3](https://github.com/codeigniter4/CodeIgniter4/tree/v4.2.3) (2022-08-06)
 [Full Changelog](https://github.com/codeigniter4/CodeIgniter4/compare/v4.2.2...v4.2.3)
 
-* security: Improve CSRF protection (for Shield CSRF security fix)
+* SECURITY: Improve CSRF protection (for Shield CSRF security fix)
 
 ## [v4.2.2](https://github.com/codeigniter4/CodeIgniter4/tree/v4.2.2) (2022-08-05)
 [Full Changelog](https://github.com/codeigniter4/CodeIgniter4/compare/v4.2.1...v4.2.2)