Show error in config in reth-rbuilder (#266)

## 📝 Summary

Before, if there was an error in the config file, it would only show the
context error "Config file parsing" but it would not show the specific
error. This PR changes that and shows the full error.

---

## ✅ I have completed the following steps:

* [x] Run `make lint`
* [x] Run `make test`
* [x] Added tests (if applicable)

crates/reth-rbuilder/src/main.rs

@@ -156,7 +156,7 @@ where
         .await;
 
         if let Err(e) = result {
-            error!("Fatal rbuilder error: {}", e);
+            error!("Fatal rbuilder error: {:#}", e);
             process::exit(1);
         }