E0026 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0026.rs

Error E0026 needs a span_label, updating it from:

error[E0026]: struct `Thing` does not have a field named `z`
  --> src/test/compile-fail/E0026.rs:19:23
   |
19 |         Thing { x, y, z } => {} //~ ERROR E0026
   |                       ^

To:

error[E0026]: struct `Thing` does not have a field named `z`
  --> src/test/compile-fail/E0026.rs:19:23
   |
19 |         Thing { x, y, z } => {} //~ ERROR E0026
   |                       ^ struct `Thing` does not have field `z`