E0303 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0007.rs

E0303 needs a span_label, updating it from:

error[E0303]: pattern bindings are not allowed after an `@`
  --> src/test/compile-fail/E0007.rs:14:26
   |
14 |         op_string @ Some(s) => {},
   |                          ^

To:

error[E0303]: pattern bindings are not allowed after an `@`
  --> src/test/compile-fail/E0007.rs:14:26
   |
14 |         op_string @ Some(s) => {},
   |                          ^ not allowed after `@`