Update CHANGELOG.md

Author: RasmusWL

CHANGELOG.md

@@ -4,6 +4,7 @@
 
 - In debug mode, debug artifacts are now uploaded even if a step in the Actions workflow fails. [#1159](https://github.com/github/codeql-action/pull/1159)
 - Update default CodeQL bundle version to 2.10.3. [#1178](https://github.com/github/codeql-action/pull/1178)
+- The combination of python2 and Pipenv is no longer supported. [#1181](https://github.com/github/codeql-action/pull/1181)
 
 ## 2.1.18 - 03 Aug 2022