📝 Update release notes

docs/release-notes.md

@@ -1,5 +1,6 @@
 ## Latest changes
 
+* Enable tests for Python 3.8-dev. PR [#465](https://github.com/tiangolo/fastapi/pull/465) by [@Jamim](https://github.com/Jamim).
 * Add support and tests for Pydantic dataclasses in `response_model`. PR [#454](https://github.com/tiangolo/fastapi/pull/454) by [@dconathan](https://github.com/dconathan).
 * Fix typo in OAuth2 JWT tutorial. PR [#447](https://github.com/tiangolo/fastapi/pull/447) by [@pablogamboa](https://github.com/pablogamboa).
 * Use the `media_type` parameter in `Body()` params to set the media type in OpenAPI for `requestBody`. PR [#439](https://github.com/tiangolo/fastapi/pull/439) by [@divums](https://github.com/divums).