Bump MSRV to 1.52.1 (#671)

.github/workflows/test.yml

@@ -81,8 +81,8 @@ jobs:
             rust: stable
           - name: beta
             rust: beta
-          - name: 1.49.0
-            rust: 1.49.0
+          - name: 1.52.1
+            rust: 1.52.1
 
     steps:
       - name: Checkout

README.md

@@ -65,7 +65,7 @@ Lettre does not provide (for now):
 
 ## Example
 
-This library requires Rust 1.49 or newer.
+This library requires Rust 1.52.1 or newer.
 To use this library, add the following to your `Cargo.toml`:
 
 

src/lib.rs

@@ -6,7 +6,7 @@
 //! * Secure defaults
 //! * Async support
 //!
-//! Lettre requires Rust 1.46 or newer.
+//! Lettre requires Rust 1.52.1 or newer.
 //!
 //! ## Features
 //!