bump sphinx theme version to a stable

mrpollo · mrpollo · commit 4b1aeb21a08f · 2015-04-07T16:53:58.000-07:00
previously the builds failed due to a package problem on the theme where
it didnt include required files for the theme.
diff --git a/requirements.txt b/requirements.txt
@@ -3,4 +3,4 @@ poster==0.8.1
 protobuf==2.6.1
 requests==2.5.1
 pymavlink>=1.1.39
-sphinx-3dr-theme>=0.0.1
+sphinx-3dr-theme>=0.0.6
