Update README.md (#8611)

Update twitter of the project's author

Author: MaertHaekkinen

README.md

@@ -185,7 +185,7 @@ Please see the [security policy][security-policy].
 [codecov]: https://codecov.io/github/encode/django-rest-framework?branch=master
 [pypi-version]: https://img.shields.io/pypi/v/djangorestframework.svg
 [pypi]: https://pypi.org/project/djangorestframework/
-[twitter]: https://twitter.com/_tomchristie
+[twitter]: https://twitter.com/starletdreaming
 [group]: https://groups.google.com/forum/?fromgroups#!forum/django-rest-framework
 [sandbox]: https://restframework.herokuapp.com/