THRIFT-5158 Update Rust generator and Rust lib,test,tutorial to only support 2018 edition
Client: rs
Patch: Allen George

This closes #2078
diff --git a/test/rs/Cargo.toml b/test/rs/Cargo.toml
index c1058f9..deffd21 100644
--- a/test/rs/Cargo.toml
+++ b/test/rs/Cargo.toml
@@ -1,6 +1,7 @@
 [package]
 name = "thrift-test"
 version = "0.1.0"
+edition = "2018"
 license = "Apache-2.0"
 authors = ["Apache Thrift Developers <dev@thrift.apache.org>"]
 publish = false