docs: update link to context.py in callbacks.rst (apache#45676)

* docs: update link to context.py in callbacks.rst

Updated the link in callbacks.rst to point to the correct context.py file in the Airflow GitHub repository.
Ensured the documentation provides accurate references to the available variables in the context.

* Update docs/apache-airflow/administration-and-deployment/logging-monitoring/callbacks.rst

Co-authored-by: Kaxil Naik <kaxilnaik@gmail.com>

---------

Co-authored-by: Elad Kalif <45845474+eladkal@users.noreply.github.com>
Co-authored-by: Kaxil Naik <kaxilnaik@gmail.com>

Author: 3 people

docs/apache-airflow/administration-and-deployment/logging-monitoring/callbacks.rst

@@ -97,4 +97,4 @@ In the following example, failures in any task call the ``task_failure_alert`` f
     to be executed in the desired event. Simply pass a list of callback functions to the callback args when defining your DAG/task
     callbacks: e.g ``on_failure_callback=[callback_func_1, callback_func_2]``
 
-Full list of variables available in ``context`` in :doc:`docs <../../templates-ref>` and `code <https://github.com/apache/airflow/blob/main/airflow/utils/context.pyi>`_.
+Full list of variables available in ``context`` in :doc:`docs <../../templates-ref>` and `code <https://github.com/apache/airflow/blob/main/task_sdk/src/airflow/sdk/definitions/context.py>`_.