[8.2.x] doc: update sprint repo link (#12297)

Co-authored-by: Florian Bruhin <[email protected]>

doc/en/index.rst

@@ -5,7 +5,7 @@
    - `Professional Testing with Python <https://python-academy.com/courses/python_course_testing.html>`_, via `Python Academy <https://www.python-academy.com/>`_ (3 day in-depth training):
       * **June 11th to 13th 2024**, Remote
       * **March 4th to 6th 2025**, Leipzig, Germany / Remote
-   - `pytest development sprint <https://github.com/pytest-dev/pytest/discussions/11655>`_, **June 17th -- 22nd 2024**
+   - `pytest development sprint <https://github.com/pytest-dev/sprint>`_, **June 17th -- 22nd 2024**
    - pytest tips and tricks for a better testsuite, `Europython 2024 <https://ep2024.europython.eu/>`_, **July 8th -- 14th 2024** (3h), Prague
 
    Also see :doc:`previous talks and blogposts <talks>`.