api: use debug formatting for reqwest errors to show full cause chain

poc-agent/src/api/mod.rs

@@ -148,7 +148,7 @@ pub(crate) async fn send_and_check(
             } else {
                 "unknown"
             };
-            anyhow::anyhow!("{} ({}): {}", cause, url, e.without_url())
+            anyhow::anyhow!("{} ({}): {:?}", cause, url, e.without_url())
         })?;
 
     let status = response.status();