Add changelog entry for PR #343

Author: actions-user

docs/changelog.md

@@ -4,6 +4,7 @@ _This project uses semantic versioning_
 
 ## UNRELEASED
 
+- Add support for `set_cost` action to have row level costs for extraction [#343](https://github.com/egraphs-good/egglog-python/pull/343)
 - Add `egraph.function_values(fn)` to export all function values like `print-function` [#340](https://github.com/egraphs-good/egglog-python/pull/340)
 - Add `egraph.stats()` method to print overall stats [#339](https://github.com/egraphs-good/egglog-python/pull/339)
 - Add `all_function_sizes` and `function_size` EGraph methods [#338](https://github.com/egraphs-good/egglog-python/pull/338)