This release introduces a new #[instrument(ret)] argument to emit an event
with the return value of an instrumented function.

Added

• #[instrument(ret)] to record the return value of a function (#1716)
• added err(Debug) argument to cause #[instrument(err)] to record errors
  with Debug rather than `Display (#1631)

Fixed

• incorrect code generation for functions returning async blocks (#1866)
• incorrect diagnostics when using rust-analyzer (#1634)

Thanks to @Swatinem, @hkmatsumoto, @cynecx, and @ciuncan for contributing to
this release!