This release of `tracing` incorporates changes from `tracing-core`
[v0.1.30][core-0.1.30] and `tracing-attributes` [v0.1.23][attrs-0.1.23],
including the new `Subscriber::on_register_dispatch` method for
performing late initialization after a `Subscriber` is registered as a
`Dispatch`, and bugfixes for the `#[instrument]` attribute.
Additionally, it fixes instances of the `bare_trait_objects` lint, which
is now a warning on `tracing`'s MSRV and will become an error in the
next edition.

### Fixed

- **attributes**: Incorrect handling of inner attributes in
  `#[instrument]`ed functions (#2307)
- **attributes**: Incorrect location of compiler diagnostic spans
  generated for type errors in `#[instrument]`ed `async fn`s (#2270)
- **attributes**: Updated `syn` dependency to fix compilation with `-Z
  minimal-versions` (#2246)
- `bare_trait_objects` warning in `valueset!` macro expansion (#2308)

### Added

- **core**: `Subscriber::on_register_dispatch` method (#2269)
- **core**: `WeakDispatch` type and `Dispatch::downgrade()` function
  (#2293)

### Changed

- `tracing-core`: updated to [0.1.30][core-0.1.30]
- `tracing-attributes`: updated to [0.1.23][attrs-0.1.23]

### Documented

- Added [`tracing-web`] and [`reqwest-tracing`] to related crates
  (#2283, #2331)

Thanks to new contributors @compiler-errors, @e-nomem, @WorldSEnder,
@Xiami2012, and @tl-rodrigo-gryzinski, as well as @jswrenn and @CAD97,
for contributing to this release!

[core-0.1.30]:
    https://github.com/tokio-rs/tracing/releases/tag/tracing-core-0.1.30
[attrs-0.1.23]:
    https://github.com/tokio-rs/tracing/releases/tag/tracing-attributes-0.1.23
[`tracing-web`]: https://crates.io/crates/tracing-web/
[`reqwest-tracing`]: https://crates.io/crates/reqwest-tracing/