TrivialFix: Remove the unused import code
In the file doc/source/conf.py, some unused import code left, this change is to
clean them up.
Change-Id: I22ad2c3f6f37e0ca80c2a0d0943492572899929e
diff --git a/doc/source/conf.py b/doc/source/conf.py
index 201d387..4e7a72d 100644
--- a/doc/source/conf.py
+++ b/doc/source/conf.py
@@ -22,10 +22,8 @@
# All configuration values have a default; values that are commented out
# serve to show the default.
-import sys
import os
import subprocess
-import warnings
import openstackdocstheme