Update texttable from 1.4.0 to 1.5.0 (#781)

Author: pyup-bot

requirements.txt

@@ -19,7 +19,7 @@ sphinx-argparse==0.2.3
 sphinx-autodoc-annotation==1.0-1
 sphinx-rtd-theme==0.4.2
 sphinx==1.8.1
-texttable==1.4.0
+texttable==1.5.0
 tornado==4.5.3
 typing==3.6.6
 virtualenv==16.0.0