Reformat src/docs/src/conf.py

After a recent change [1], python black started to complain. Since we updated
docs only in that PR we skipped the python black check. So reformat to make the
checker happy.

In the future make sure to run python black formatting even when we make
docs-only changes.

[1] https://github.com/apache/couchdb/pull/4208
diff --git a/build-aux/Jenkinsfile.pr b/build-aux/Jenkinsfile.pr
index 1c3dc2f..f24fed1 100644
--- a/build-aux/Jenkinsfile.pr
+++ b/build-aux/Jenkinsfile.pr
@@ -117,6 +117,9 @@
       }
       steps {
         sh '''
+          make python-black
+        '''
+        sh '''
           (cd src/docs && make check)
         '''
       }
diff --git a/src/docs/src/conf.py b/src/docs/src/conf.py
index c6c583a..05d3a42 100644
--- a/src/docs/src/conf.py
+++ b/src/docs/src/conf.py
@@ -77,7 +77,7 @@
     "rtd_ver": os.environ.get("READTHEDOCS_VERSION_NAME") or "latest",
 }
 
-http_index_shortname = 'API Reference'
+http_index_shortname = "API Reference"
 
 http_index_localname = "API Quick Reference"