chore: Clean up some formatting in exercises

exercises/if/if1.rs

@@ -1,6 +1,6 @@
 // if1.rs
 
-pub fn bigger(a: i32, b:i32) -> i32 {
+pub fn bigger(a: i32, b: i32) -> i32 {
     // Complete this function to return the bigger number!
     // Do not use:
     // - return