TrivialFix: Remove the unused import code

Remove the unused import code in doc/source/conf.py

Change-Id: Idd3de97e2752eb6a04b2040ea1dd88da5bb91b04
diff --git a/doc/source/conf.py b/doc/source/conf.py
index 4e7a72d..0cfdf34 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -25,8 +25,6 @@
 import os
 import subprocess
 
-import openstackdocstheme
-
 # Build the plugin registry
 def build_plugin_registry(app):
     root_dir = os.path.dirname(