:art: use updated ast

diff --git a/ast b/ast
index 58ede83c62af55bec048d0ce99081aa829540612..b26fd84a653b941bb73b5e2395eae27e2e5b4dba 160000 (submodule)
--- a/ast
+++ b/ast
@@ -1 +1 @@
-Subproject commit 58ede83c62af55bec048d0ce99081aa829540612
+Subproject commit b26fd84a653b941bb73b5e2395eae27e2e5b4dba