E0453 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0453.rs

E0453 needs a span_label and a span_note changed to a span_label, updating it from:

error[E0453]: allow(non_snake_case) overruled by outer forbid(non_snake_case)
  --> src/test/compile-fail/E0453.rs:13:9
   |
13 | #[allow(non_snake_case)] //~ ERROR E0453
   |         ^^^^^^^^^^^^^^
   |
note: `forbid` lint level set here
  --> src/test/compile-fail/E0453.rs:11:11
   |
11 | #![forbid(non_snake_case)]
   |           ^^^^^^^^^^^^^^

To:

error[E0453]: allow(non_snake_case) overruled by outer forbid(non_snake_case)
  --> src/test/compile-fail/E0453.rs:13:9
   |
11 | #![forbid(non_snake_case)]
   |           -------------- `forbid` level set here
12 |
13 | #[allow(non_snake_case)] //~ ERROR E0453
   |         ^^^^^^^^^^^^^^ overruled by previous forbid