Set the edition to 2021

Cargo.toml

@@ -10,6 +10,7 @@ description = """
 Support for matching file paths against Unix shell style patterns.
 """
 categories = ["filesystem"]
+edition = "2021"
 rust-version = "1.63.0"
 
 [dev-dependencies]

README.md

@@ -16,12 +16,6 @@ To use `glob`, add this to your `Cargo.toml`:
 glob = "0.3.2"
 ```
 
-If you're using Rust 1.30 or earlier, or edition 2015, add this to your crate root:
-
-```rust
-extern crate glob;
-```
-
 ## Examples
 
 Print all jpg files in /media/ and all of its subdirectories.

src/lib.rs

@@ -64,11 +64,7 @@
 #![allow(clippy::while_let_loop)]
 
 #[cfg(test)]
-#[macro_use]
-extern crate doc_comment;
-
-#[cfg(test)]
-doctest!("../README.md");
+doc_comment::doctest!("../README.md");
 
 use std::cmp;
 use std::cmp::Ordering;
@@ -319,7 +315,7 @@ impl Error for GlobError {
     }
 
     #[allow(unknown_lints, bare_trait_objects)]
-    fn cause(&self) -> Option<&Error> {
+    fn cause(&self) -> Option<&dyn Error> {
         Some(&self.error)
     }
 }

tests/glob-std.rs

@@ -12,9 +12,6 @@
 
 #![cfg_attr(test, deny(warnings))]
 
-extern crate glob;
-extern crate tempfile;
-
 use glob::{glob, glob_with};
 use std::env;
 use std::fs;