Update changelog and version for 1.26.4

Author: sean-mcmanus

Extension/CHANGELOG.md

@@ -1,5 +1,9 @@
 # C/C++ for Visual Studio Code Changelog
 
+## Version 1.26.4: September 8, 2025
+* Update GitHub Copilot APIs. [PR #13877](https://github.com/microsoft/vscode-cpptools/pull/13877)
+  * Thank you for the contribution. [@dbaeumer (Dirk Bäumer)](https://github.com/dbaeumer)
+
 ## Version 1.26.3: June 24, 2025
 ### New Feature
 * Improve the context provided for C++ Copilot suggestions.

Extension/package.json

@@ -2,7 +2,7 @@
     "name": "cpptools",
     "displayName": "C/C++",
     "description": "C/C++ IntelliSense, debugging, and code browsing.",
-    "version": "1.26.3-main",
+    "version": "1.26.4-main",
     "publisher": "ms-vscode",
     "icon": "LanguageCCPP_color_128x.png",
     "readme": "README.md",