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/lib/rs/Cargo.toml b/lib/rs/Cargo.toml
index 0626da8..674a4c3 100644
--- a/lib/rs/Cargo.toml
+++ b/lib/rs/Cargo.toml
@@ -1,6 +1,7 @@
 [package]
 name = "thrift"
 description = "Rust bindings for the Apache Thrift RPC system"
+edition = "2018"
 version = "0.14.0"
 license = "Apache-2.0"
 authors = ["Apache Thrift Developers <dev@thrift.apache.org>"]