📝 Update release notes

[skip ci]

docs/en/docs/release-notes.md

@@ -29,6 +29,7 @@ hide:
 
 ### Internal
 
+* 🔧 Update sponsors: Remove TestMu. PR [#15688](https://github.com/fastapi/fastapi/pull/15688) by [@tiangolo](https://github.com/tiangolo).
 * ⬆ Bump the python-packages group across 1 directory with 11 updates. PR [#15683](https://github.com/fastapi/fastapi/pull/15683) by [@dependabot[bot]](https://github.com/apps/dependabot).
 * ⬆ Bump aiohttp from 3.13.4 to 3.14.0. PR [#15681](https://github.com/fastapi/fastapi/pull/15681) by [@dependabot[bot]](https://github.com/apps/dependabot).
 * ⬆ Bump the github-actions group with 2 updates. PR [#15682](https://github.com/fastapi/fastapi/pull/15682) by [@dependabot[bot]](https://github.com/apps/dependabot).