Ensure exec_command() stdout/stderr stays piped

We use `Stdio::piped()` in virtually every other instance of
`tokio::process::Command`. This accidental omission was an oversight.

Author: ebkalderon

src/container.rs

@@ -150,7 +150,12 @@ impl Drop for Container {
 }
 
 async fn exec_command(cmd: &mut Command) -> anyhow::Result<()> {
-    let output = cmd.output().await?;
+    let output = cmd
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
+        .output()
+        .await?;
+
     if !output.status.success() {
         let stderr = std::str::from_utf8(&output.stderr)?;
         return Err(anyhow!("`{:?}` returned: [{}]", cmd, stderr));