tracing 0.1.37

This release of tracing incorporates changes from tracing-core
v0.1.30 and tracing-attributes v0.1.23,
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 fns (#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
• tracing-attributes: updated to 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!