Auto merge of #7664 - matthiaskrgr:bump_to_2021, r=flip1995

bump clippy crates to edition 2021

Also helps with dogfooding edition 2021 a bit. :)
Tests passed locally.

---

changelog: bump edition from 2018 to 2021

Cargo.toml

@@ -8,7 +8,7 @@ license = "MIT OR Apache-2.0"
 keywords = ["clippy", "lint", "plugin"]
 categories = ["development-tools", "development-tools::cargo-plugins"]
 build = "build.rs"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [[bin]]

clippy_dev/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "clippy_dev"
 version = "0.0.1"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 bytecount = "0.6"

clippy_lints/Cargo.toml

@@ -6,7 +6,7 @@ repository = "https://github.com/rust-lang/rust-clippy"
 readme = "README.md"
 license = "MIT OR Apache-2.0"
 keywords = ["clippy", "lint", "plugin"]
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 cargo_metadata = "0.12"

clippy_lints/src/matches.rs

@@ -183,8 +183,8 @@ declare_clippy_lint! {
     /// ```rust
     /// let x = 5;
     /// match x {
-    ///     1...10 => println!("1 ... 10"),
+    ///     1..=10 => println!("1 ... 10"),
-    ///     5...15 => println!("5 ... 15"),
+    ///     5..=15 => println!("5 ... 15"),
     ///     _ => (),
     /// }
     /// ```

clippy_utils/Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "clippy_utils"
 version = "0.1.57"
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]