Set the edition to 2021, run fix --edition, make necessary updates.

Cargo.toml

@@ -22,6 +22,7 @@
 name = "ned"
 version = "1.3.2"
 authors = ["Nev Delap <[email protected]>"]
+edition = "2021"
 
 [dependencies]
 ansi_term = "0.12.*"

src/tests/files.rs

@@ -202,7 +202,7 @@ fn test(args: &str, expected_file_names: &[&str]) {
         .split_whitespace()
         .map(|arg| arg.to_string())
         .collect::<Vec<String>>();
-    env::set_var("NED_DEFAULTS", "");
+    unsafe { env::set_var("NED_DEFAULTS", "") };
     let options_with_defaults = OptionsWithDefaults::new(make_opts(), &args).unwrap();
     let parameters = get_parameters(&options_with_defaults).unwrap();
     let paths = Files::new(&parameters, &parameters.globs[0]);

src/tests/matches.rs

@@ -1687,7 +1687,7 @@ fn really_test(
         .map(|arg| arg.to_string())
         .collect::<Vec<String>>();
     args.insert(0, pattern.to_string());
-    env::set_var("NED_DEFAULTS", "");
+    unsafe { env::set_var("NED_DEFAULTS", "") };
     let options_with_defaults = OptionsWithDefaults::new(make_opts(), &args).unwrap();
     let parameters = get_parameters(&options_with_defaults).unwrap();