Upgrade to Rust 2021 edition

Author: orhun

.github/workflows/ci.yml

@@ -8,7 +8,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        rust: ["1.54.0", "1.60.0"]
+        rust: ["1.56.1", "1.60.0"]
     runs-on: ${{ matrix.os }}
     steps:
     - name: Checkout source

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "rust-script"
 version = "0.22.0"
-edition = "2018"
+edition = "2021"
 authors = ["Fredrik Fornwall <fredrik@fornwall.net>"]
 description = "Command-line tool to run Rust \"scripts\" which can make use of crates."
 homepage = "https://rust-script.org"

README.md

@@ -29,7 +29,7 @@ $ ./script.rs
 A random number: 9240261453149857564
 ```
 
-Rust version 1.54 or newer required.
+Rust version 1.56.1 or newer required.
 
 See the [documentation at rust-script.org](https://rust-script.org).
 

src/main.rs

@@ -95,7 +95,6 @@ impl BuildKind {
 
 fn parse_args() -> Args {
     use clap::{Arg, ArgGroup, Command};
-    use std::iter::FromIterator;
     let version = option_env!("CARGO_PKG_VERSION").unwrap_or("unknown");
     let about = r#"Compiles and runs a Rust script."#;