E0496 needs to be updated to new format

[sophiajt]

From: src/test/compile-fail/E0496.rs

E0496 needs a span_label and a span_note converted to a span_label, updating this:

error[E0496]: lifetime name `'a` shadows a lifetime name that is already in scope
  --> src/test/compile-fail/E0496.rs:16:10
   |
16 |     fn f<'a>(x: &'a i32) { //~ ERROR E0496
   |          ^^
   |
note: shadowed lifetime `'a` declared here
  --> src/test/compile-fail/E0496.rs:15:6
   |
15 | impl<'a> Foo<'a> {
   |      ^^

To:

error[E0496]: lifetime name `'a` shadows a lifetime name that is already in scope
  --> src/test/compile-fail/E0496.rs:16:10
   |
15 | impl<'a> Foo<'a> {
   |      -- first declared here
16 |     fn f<'a>(x: &'a i32) { //~ ERROR E0496
   |          ^^ lifetime 'a already in scope