fix: Allow multiple versions of crates (#388)

Downstream dependencies may have different versions of crates, and
this could change at any time. Disable this lint so that clippy
builds are not at the mercy of donwstream dependencies.

Author: bahildebrand

lambda-runtime-api-client/src/lib.rs

@@ -1,5 +1,6 @@
 #![deny(clippy::all, clippy::cargo)]
 #![warn(missing_docs, nonstandard_style, rust_2018_idioms)]
+#![warn(clippy::multiple_crate_versions)]
 
 //! This crate includes a base HTTP client to interact with
 //! the AWS Lambda Runtime API.