* tracing: bump attrs and core versions

Signed-off-by: Eliza Weisman <eliza@buoyant.io>

* tracing: prepare to release 0.1.10

Added

- Support for destructuring in arguments to `#[instrument]`ed functions
  (#397)
- Generated field for `self` parameters when `#[instrument]`ing methods
  (#397)
- Optional `skip` argument to `#[instrument]` for excluding function
  parametersfrom generated spans (#359)
- Added `dispatcher::set_default` and `subscriber::set_default` APIs,
  which return a drop guard (#388)

Fixed

- Some minor documentation errors (#356, #370)

Signed-off-by: Eliza Weisman <eliza@buoyant.io>