v5.7.0

While this is a semver-minor release, there's potential for it to have
knock-on effects due to the syn2 upgrade. There's been issues as this new
version propagates between syn/thiserror versions (for example, see a similar
change in eyre).

The other thing of note is that backtrace printing is now much better! Try
the hook and see for yourself!

Features

• deps: update to syn2 (#247) (a2157205)
• panic: improved backtrace handling (b0453215)

Bug Fixes

• colors: change unicode to default to ansi (#249) (159f2b35)
• tests: disable doctest that doesn't work with default feature flags (#248) (0b445dc2)