chore: update changelog for 0.19.4 (#6414)

CHANGELOG.md

@@ -69,6 +69,14 @@ Canonical reference for changes, improvements, and bugfixes for Boundary.
   Boundary to conform with RFC 5952.
   ([PR](https://github.com/hashicorp/boundary/pull/5599))
 
+## 0.19.4 (2026/02/10)
+
+### Security
+
+* Go version bumped to 1.25.7 to address CVE-2025-61730 ([PR](https://github.com/hashicorp/boundary/pull/6409))
+* Go Cryptography dependency update to address CVE-2025-58181 and CVE-2025-47914
+  ([PR](https://github.com/hashicorp/boundary/pull/6272))
+
 ## 0.19.3 (2025/07/10)
 ### New and Improved