Updated `rules_rust` version to `0.3.1` (#1296)

diff --git a/version.bzl b/version.bzl
index 6a3efba..f8b6b9a 100644
--- a/version.bzl
+++ b/version.bzl
@@ -1,3 +1,3 @@
 """The version of rules_rust."""
 
-VERSION = "0.3.0"
+VERSION = "0.3.1"