Move to the 2021 edition

Cargo.toml

@@ -3,7 +3,7 @@ name = "teloxide-macros"
 version = "0.7.0"
 description = "The teloxide's procedural macros"
 license = "MIT"
-edition = "2018"
+edition = "2021"
 
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 

src/error.rs

@@ -17,8 +17,6 @@ pub(crate) fn compile_error_at(msg: &str, sp: Span) -> Error {
     use proc_macro2::{
         Delimiter, Group, Ident, Literal, Punct, Spacing, TokenTree,
     };
-    use std::iter::FromIterator;
-
     // compile_error! { $msg }
     let ts = TokenStream::from_iter(vec![
         TokenTree::Ident(Ident::new("compile_error", sp)),