Update changelog for 1.20.2 (2nd time) (#12228)

* Update changelog

Author: sean-mcmanus

Extension/CHANGELOG.md

@@ -1,7 +1,8 @@
 # C/C++ for Visual Studio Code Changelog
 
-## Version 1.20.2: April 17, 2024
+## Version 1.20.2: April 22, 2024
 ### Bug Fixes
+* Fix non-existent relative path variables not showing a warning in `c_cpp_properties.json` (and other related issues). [#12089](https://github.com/microsoft/vscode-cpptools/issues/12089)
 * Fix duplicate URIs in calls to provideConfigurations. [#12177](https://github.com/microsoft/vscode-cpptools/issues/12177)
 * Fix a crash and deadlock with a high `C_Cpp.loggingLevel`. [#12194](https://github.com/microsoft/vscode-cpptools/issues/12194)
 * Fix handling of `-iquote` for code analysis and `#include` completions. [#12198](https://github.com/microsoft/vscode-cpptools/issues/12198)