E0023 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0023.rs

E0023 needs span_labels, taking it from:

error[E0023]: this pattern has 1 fields, but the corresponding variant has 2 fields
  --> src/test/compile-fail/E0023.rs:19:9
   |
19 |         Fruit::Apple(a) => {}, //~ ERROR E0023
   |         ^^^^^^^^^^^^^^^

To:

error[E0023]: this pattern has 1 fields, but the corresponding variant has 2 fields
  --> src/test/compile-fail/E0023.rs:19:9
   |
19 |         Fruit::Apple(a) => {}, //~ ERROR E0023
   |         ^^^^^^^^^^^^^^^ expected 2 fields, found 1

Bonus: "this pattern has 1 fields" isn't good English. You could detect the number and change "fields" to "field" or reword this to be "this pattern has 1 field(s)"