📝 Update release notes

docs/en/docs/release-notes.md

@@ -11,6 +11,7 @@ hide:
 
 ### Refactors
 
+* ♻️ Simplify string format with f-strings in `fastapi/utils.py`. PR [#10576](https://github.com/tiangolo/fastapi/pull/10576) by [@eukub](https://github.com/eukub).
 * 🔧 Fix Ruff configuration unintentionally enabling and re-disabling mccabe complexity check. PR [#10893](https://github.com/tiangolo/fastapi/pull/10893) by [@jiridanek](https://github.com/jiridanek).
 * ✅ Re-enable test in `tests/test_tutorial/test_header_params/test_tutorial003.py` after fix in Starlette. PR [#10904](https://github.com/tiangolo/fastapi/pull/10904) by [@ooknimm](https://github.com/ooknimm).