Update to rust 1.56 and 2021 edition

.clippy.toml

@@ -1 +1 @@
-msrv = "1.31.0"
+msrv = "1.56.0"

Cargo.toml

@@ -2,8 +2,8 @@
 name = "serde_yaml"
 version = "0.8.25" # remember to update html_root_url, and readme for major versions
 authors = ["David Tolnay <dtolnay@gmail.com>"]
-edition = "2018"
-rust-version = "1.46"
+edition = "2021"
+rust-version = "1.56"
 license = "MIT OR Apache-2.0"
 description = "YAML support for Serde"
 repository = "https://github.com/dtolnay/serde-yaml"

src/lib.rs

@@ -76,8 +76,10 @@
     clippy::should_implement_trait,
     // things are often more readable this way
     clippy::cast_lossless,
+    clippy::checked_conversions,
     clippy::if_not_else,
     clippy::manual_assert,
+    clippy::match_like_matches_macro,
     clippy::match_same_arms,
     clippy::module_name_repetitions,
     clippy::needless_pass_by_value,
@@ -95,6 +97,8 @@
     // noisy
     clippy::missing_errors_doc,
     clippy::must_use_candidate,
+    // todo
+    clippy::manual_strip,
 )]
 
 pub use crate::de::{from_reader, from_slice, from_str, Deserializer};