Add changelog note

Author: henrymercer

CHANGELOG.md

@@ -4,6 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
+- The CodeQL Action now requires CodeQL version 2.10.5 or later. For more information, see the corresponding changelog entry for CodeQL Action version 2.21.8. [#1907](https://github.com/github/codeql-action/pull/1907)
 - Update default CodeQL bundle version to 2.14.6. [#1897](https://github.com/github/codeql-action/pull/1897)
 - We are rolling out a feature in October 2023 that will improve the success rate of C/C++ autobuild. [#1889](https://github.com/github/codeql-action/pull/1889)
 - We are rolling out a feature in October 2023 that will provide specific file coverage information for C and C++, Java and Kotlin, and JavaScript and TypeScript. Currently file coverage information for each of these pairs of languages is grouped together. [#1903](https://github.com/github/codeql-action/pull/1903)