E0393 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0393.rs

E0393 needs a span_label, updated title, and a note, changing it from:

error[E0393]: the type parameter `T` must be explicitly specified in an object type because its default value `Self` references the type `Self`
  --> src/test/compile-fail/E0393.rs:13:43
   |
13 | fn together_we_will_rule_the_galaxy(son: &A) {} //~ ERROR E0393
   |                                           ^

To:

error[E0393]: the type parameter `T` must be explicitly specified
  --> src/test/compile-fail/E0393.rs:13:43
   |
13 | fn together_we_will_rule_the_galaxy(son: &A) {} //~ ERROR E0393
   |                                           ^ missing reference to `T`
   |
   = note: because of the default `Self` reference, type parameters must be specified on object types