Downgrade docutils to 0.19

When we are trying to install Sphinx which is pinned to 5.3.0, we get the following dependency error:

The conflict is caused by:
    sphinx 5.3.0 depends on docutils<0.20 and >=0.14
    The user requested (constraint) docutils==0.20.1

See apache/airflow#31366

2.7.3/constraints-3.8.txt

@@ -271,7 +271,7 @@ distributed==2023.4.1
 dnspython==2.4.2
 docker==6.1.3
 docopt==0.6.2
-docutils==0.20.1
+docutils==0.19
 duckdb==0.9.1
 ecdsa==0.18.0
 elastic-transport==8.10.0