THRIFT-5600: rust lib to upgrade to edition 2021
Client: rs
Patch: Jiayu Liu

This closes #2628
diff --git a/lib/rs/test_recursive/Cargo.toml b/lib/rs/test_recursive/Cargo.toml
index 6b2aa85..28dbf38 100644
--- a/lib/rs/test_recursive/Cargo.toml
+++ b/lib/rs/test_recursive/Cargo.toml
@@ -3,7 +3,7 @@
 description = "Test namespace support in generated thrift files using recursive Make generation"
 version = "0.1.0"
 authors = ["Allen George <allengeorge@apache.org>"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 thrift = { path = "../" }