doc: changelog

Author: aignas

CHANGELOG.md

@@ -78,6 +78,9 @@ Unreleased changes template.
 * (toolchains) Do not try to run `chmod` when downloading non-windows hermetic toolchain
   repositories on Windows. Fixes
   [#2660](https://github.com/bazel-contrib/rules_python/issues/2660).
+* (toolchains) The toolchain matching is has been fixed when writing
+  transitions transitioning on the `python_version` flag.
+  Fixes [#2685](https://github.com/bazel-contrib/rules_python/issues/2685).
 
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