update msrv to 1.56 (#2777)

* update msrv to 1.56

* remove transitive dashmap dependency

closes #2747

actix-web/CHANGES.md

@@ -7,6 +7,9 @@
 - Add `ServiceConfig::default_service()`. [#2338] [#2743]
 - Implement `ResponseError` for `std::convert::Infallible`
 
+### Changed
+- Minimum supported Rust version (MSRV) is now 1.56 due to transitive `hashbrown` dependency.
+
 ### Fixed
 - Clear connection-level data on `HttpRequest` drop. [#2742]
 

actix-web/README.md

@@ -7,7 +7,7 @@
 
 [![crates.io](https://img.shields.io/crates/v/actix-web?label=latest)](https://crates.io/crates/actix-web)
 [![Documentation](https://docs.rs/actix-web/badge.svg?version=4.0.1)](https://docs.rs/actix-web/4.0.1)
-![MSRV](https://img.shields.io/badge/rustc-1.54+-ab6000.svg)
+![MSRV](https://img.shields.io/badge/rustc-1.56+-ab6000.svg)
 ![MIT or Apache 2.0 licensed](https://img.shields.io/crates/l/actix-web.svg)
 [![Dependency Status](https://deps.rs/crate/actix-web/4.0.1/status.svg)](https://deps.rs/crate/actix-web/4.0.1)
 <br />
@@ -33,7 +33,7 @@
 - SSL support using OpenSSL or Rustls
 - Middlewares ([Logger, Session, CORS, etc](https://actix.rs/docs/middleware/))
 - Integrates with the [`awc` HTTP client](https://docs.rs/awc/)
-- Runs on stable Rust 1.54+
+- Runs on stable Rust 1.56+
 
 ## Documentation