Fix Parser::break_up_float's right span

[ShE3py]

use std::mem::offset_of;

fn main() {
    offset_of!((u8,), 0.0);
}

Before:

error[E0609]: no field `0` on type `u8`
    --> ./main.rs:4:25
     |
4    |       offset_of!((u8,), 0.0);
     |  _____--------------------^-
     | |     |
     | |     in this macro invocation
5    | | }
...    |
     |
     = note: this error originates in the macro `offset_of` (in Nightly builds, run with -Z macro-backtrace for more info)

error: aborting due to 1 previous error

After:

error[E0609]: no field `0` on type `u8`
 --> ./main.rs:4:25
  |
4 |     offset_of!((u8,), 0.0);
  |                         ^

error: aborting due to 1 previous error

---

@rustbot label +A-parser +D-imprecise-spans

[rustbot]

r? @chenyukang

rustbot has assigned @chenyukang.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

[fmease]

cc #123877 (comment)

[fmease]

@bors r+ rollup

[bors]

📌 Commit 4cb5849 has been approved by fmease

It is now in the queue for this repository.

[bors]

☔ The latest upstream changes (presumably #130357) made this pull request unmergeable. Please resolve the merge conflicts.