Update changelog

Author: aeisenberg

extensions/ql-vscode/CHANGELOG.md

@@ -3,6 +3,7 @@
 ## [UNRELEASED]
 
 - Add new supported source and sink kinds in the CodeQL Model Editor [#3511](https://github.com/github/vscode-codeql/pull/3511)
+- Fix a bug where the test explorer wouldn't display certain tests. [#3527](https://github.com/github/vscode-codeql/pull/3527)
 
 ## 1.12.4 - 20 March 2024