Update rust dependencies to latest version.

diff --git a/src/ext/rust b/src/ext/rust
index fbc0c25785696a25b9cbc09ed645cc8d404ee0f6..40759064756f668c25ad1347faa793fc0d6afe8b 160000 (submodule)
--- a/src/ext/rust
+++ b/src/ext/rust
@@ -1 +1 @@
-Subproject commit fbc0c25785696a25b9cbc09ed645cc8d404ee0f6
+Subproject commit 40759064756f668c25ad1347faa793fc0d6afe8b