docs: Bump version to 1.3.8.

Should have done it before tagging...

docs/conf.py

@@ -60,7 +60,7 @@ copyright = '2014, Damien P. George'
 # The short X.Y version.
 version = '1.3'
 # The full version, including alpha/beta/rc tags.
-release = '1.3.7'
+release = '1.3.8'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.