move to twig 1.9.0

diff --git a/twig b/twig
index ff61094..31f0592 160000 (submodule)
--- a/twig
+++ b/twig
@@ -1 +1 @@
-Subproject commit ff61094aa374808c3f2c1a385352226090e37ecf
+Subproject commit 31f05925258063a363178691be6988bde78ab5fb