Revert "RUST-1263 Bump MSRV to 1.53 (#639) (#641)"

This reverts commit cb45c29.

Author: patrickfreed

.evergreen/config.yml

@@ -1289,9 +1289,9 @@ axes:
   - id: "extra-rust-versions"
     values:
       - id: "min"
-        display_name: "1.53 (minimum supported version)"
+        display_name: "1.51 (minimum supported version)"
         variables:
-          RUST_VERSION: "1.53.0"
+          RUST_VERSION: "1.51.0"
       - id: "nightly"
         display_name: "nightly"
         variables:

README.md

@@ -29,7 +29,7 @@ This repository contains the officially supported MongoDB Rust driver, a client
 
 ## Installation
 ### Requirements
-- Rust 1.53+
+- Rust 1.51+
 - MongoDB 3.6+
 
 ### Importing
@@ -358,7 +358,7 @@ Commits to master are run automatically on [evergreen](https://evergreen.mongodb
 
 ## Minimum supported Rust version (MSRV)
 
-The MSRV for this crate is currently 1.53.0. This will be rarely be increased, and if it ever is,
+The MSRV for this crate is currently 1.51.0. This will be rarely be increased, and if it ever is,
 it will only happen in a minor or major version release.
 
 ## License

src/lib.rs

@@ -8,7 +8,7 @@
 //! # Installation
 //!
 //! ## Requirements
-//! - Rust 1.53+
+//! - Rust 1.51+
 //! - MongoDB 3.6+
 //!
 //! ## Importing
@@ -283,7 +283,7 @@
 //!
 //! ## Minimum supported Rust version (MSRV)
 //!
-//! The MSRV for this crate is currently 1.53.0. This will be rarely be increased, and if it ever is,
+//! The MSRV for this crate is currently 1.51.0. This will be rarely be increased, and if it ever is,
 //! it will only happen in a minor or major version release.
 
 #![warn(missing_docs)]