rustfmt the exercises

Signed-off-by: Eddy Petrisor <eddy.petrisor@gmail.com>

exercises/error_handling/option1.rs

@@ -11,7 +11,10 @@ fn main() {
     println!("The last item in the list is {:?}", last);
 
     let second_to_last = list.pop().unwrap();
-    println!("The second-to-last item in the list is {:?}", second_to_last);
+    println!(
+        "The second-to-last item in the list is {:?}",
+        second_to_last
+    );
 }