Fix formatting

Author: mo8it

rustlings-macros/info.toml

@@ -763,8 +763,8 @@ hint = """
 Notice how the trait takes ownership of `self` and returns `Self`.
 
 Although the signature of `append_bar` in the trait takes `self` as argument,
-the implementation can take `mut self` instead. This is possible because  
-the value is owned anyway."""
+the implementation can take `mut self` instead. This is possible because the
+value is owned anyway."""
 
 [[exercises]]
 name = "traits3"