style: fix 2 clippy lint unless_vec & unused_io_amount (#751)

Author: SteveLauC

src/config.rs

@@ -477,7 +477,7 @@ impl ConfigFile {
 
         let config_directory = config_directory();
 
-        let possible_config_paths = vec![
+        let possible_config_paths = [
             config_directory.join("topgrade.toml"),
             config_directory.join("topgrade/topgrade.toml"),
         ];

src/steps/vim.rs

@@ -57,8 +57,8 @@ fn upgrade(command: &mut Executor, ctx: &ExecutionContext) -> Result<()> {
         let status = output.status;
 
         if !status.success() || ctx.config().verbose() {
-            io::stdout().write(&output.stdout).ok();
-            io::stderr().write(&output.stderr).ok();
+            io::stdout().write_all(&output.stdout).ok();
+            io::stderr().write_all(&output.stderr).ok();
         }
 
         if !status.success() {