Bump MSRV to 1.71

Author: taiki-e

Cargo.toml

@@ -6,7 +6,7 @@ name = "async-process"
 version = "2.4.0"
 authors = ["Stjepan Glavina <stjepang@gmail.com>"]
 edition = "2021"
-rust-version = "1.70"
+rust-version = "1.71"
 description = "Async interface for working with processes"
 license = "Apache-2.0 OR MIT"
 repository = "https://github.com/smol-rs/async-process"