E0306 needs to be updated to new format

[sophiajt]

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

Error E0306 needs a span_label and a title update, updating it from:

error[E0306]: expected usize for repeat count, found tuple
  --> src/test/compile-fail/repeat_count.rs:18:17
   |
18 |     let b = [0; ()];
   |                 ^^

to:

error[E0306]: expected `usize` for repeat count, found tuple
  --> src/test/compile-fail/repeat_count.rs:18:17
   |
18 |     let b = [0; ()];
   |                 ^^ expected `usize`