E0445 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0445.rs

E0445 needs a span_label, updating it from:

error[E0445]: private trait in public interface
  --> src/test/compile-fail/E0445.rs:15:17
   |
15 | pub trait Bar : Foo {} //~ ERROR E0445
   |                 ^^^

To:

error[E0445]: private trait in public interface
  --> src/test/compile-fail/E0445.rs:15:17
   |
15 | pub trait Bar : Foo {} //~ ERROR E0445
   |                 ^^^ private trait can't be public