Make Clippy even happier

Author: smoelius

tests/suite/cli_rustup.rs

@@ -3092,11 +3092,7 @@ override nightly-[HOST_TRIPLE]
 async fn rustup_toolchain_source_config() {
     let cx = CliTestContext::new(Scenario::SimpleV2).await;
     let toolchain_file = cx.config.current_dir().join("rust-toolchain.toml");
-    raw::write_file(
-        &toolchain_file,
-        &"[toolchain]\nchannel='nightly'".to_string(),
-    )
-    .unwrap();
+    raw::write_file(&toolchain_file, "[toolchain]\nchannel='nightly'").unwrap();
     cx.config
         .expect(["cargo", "--echo-rustup-toolchain-source"])
         .await