lower MSRV to 1.57.0

This line uses the Display trait for io::ErrorKind which was
stabilized in Rust 1.60.0. We can set MSRV all the way back to
1.57.0 by replacing it with a pretty-print.

Closes #2460.

.github/workflows/msrv-rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
-channel = "1.60.0"
+channel = "1.57.0"
 components = ["rustfmt", "rust-src"]

helix-view/src/handlers/dap.rs

@@ -302,7 +302,9 @@ pub async fn handle_debugger_message(&mut self, payload: helix_dap::Payload) ->
                                     .arg(arguments.args.join(" "))
                                     .spawn()
                                     .unwrap(),
-                                e => panic!("Error to start debug console: {}", e),
+                                // TODO replace the pretty print {:?} with a regular format {}
+                                // when the MSRV is raised to 1.60.0
+                                e => panic!("Error to start debug console: {:?}", e),
                             })
                     } else {
                         std::process::Command::new("tmux")