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/tutorial/rs/Cargo.toml b/tutorial/rs/Cargo.toml
index 60f02d7..d8e2a9a 100644
--- a/tutorial/rs/Cargo.toml
+++ b/tutorial/rs/Cargo.toml
@@ -1,6 +1,7 @@
 [package]
 name = "thrift-tutorial"
 version = "0.1.0"
+edition = "2018"
 license = "Apache-2.0"
 authors = ["Apache Thrift Developers <dev@thrift.apache.org>"]
 exclude = ["Makefile*", "shared.rs", "tutorial.rs"]