chore: Switch to thiserror 2.0.4 where possible

[torokati44]

Our "jpegxr" crate is still to be updated, because it doesn't have Dependabot set up.
EDIT: Done.

[torokati44]

See: ruffle-rs/jpegxr#4
EDIT: Merged.

[torokati44]

Uh, the CI failure seems to be bogus...?
https://github.com/ruffle-rs/ruffle/actions/runs/12021815997/job/33512985856?pr=18761#step:6:1096

error: the following explicit lifetimes could be elided: 'gc
 --> core/src/avm1/error.rs:5:16
  |
5 | pub enum Error<'gc> {
  |                ^^^
  |
  = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_lifetimes
  = note: `-D clippy::needless-lifetimes` implied by `-D warnings`
  = help: to override `-D warnings` add `#[allow(clippy::needless_lifetimes)]`
help: elide the lifetimes
  |
5 - pub enum Error<'gc> {
5 + pub enum Error'_> {
  |

See: rust-lang/rust-clippy#12789 and/or rust-lang/rust-clippy#12908.

[torokati44]

The beta clippy lint got fixed by dtolnay/thiserror#391 in 2.0.4, it no longer has to be suppressed.