cli: log to stderr

src/main.rs

@@ -273,11 +273,11 @@ async fn main() {
             for s in samples {
                 match s {
                     Err(e) => {
-                        println!("Failed to fetch: {}", e);
+                        eprintln!("Failed to fetch: {}", e);
                     }
                     Ok(None) => {}
                     Ok(Some(ingested)) => {
-                        println!("{:?}", ingested)
+                        eprintln!("{:?}", ingested)
                     }
                 }
             }