[AIRFLOW-5209] Bump Sphinx version to fix doc build (#5814)
[AIRFLOW-5209] Bump Sphinx version to fix doc build (#5814)


(cherry picked from commit 34fbd029f70c9f51de93ab3d3bfc6c72bb8d5bf3)

owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow,owlabs/incubator-airflow